WO2020129481A1 - Lithium secondary battery - Google Patents

Lithium secondary battery Download PDF

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Publication number
WO2020129481A1
WO2020129481A1 PCT/JP2019/044550 JP2019044550W WO2020129481A1 WO 2020129481 A1 WO2020129481 A1 WO 2020129481A1 JP 2019044550 W JP2019044550 W JP 2019044550W WO 2020129481 A1 WO2020129481 A1 WO 2020129481A1
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WIPO (PCT)
Prior art keywords
region
active material
positive electrode
secondary battery
negative electrode
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PCT/JP2019/044550
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French (fr)
Japanese (ja)
Inventor
真彦 日比野
俊介 水上
貴大 中西
雄樹 藤田
Original Assignee
日本碍子株式会社
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Application filed by 日本碍子株式会社 filed Critical 日本碍子株式会社
Priority to JP2020561222A priority Critical patent/JP7190509B2/en
Priority to KR1020217015200A priority patent/KR102618405B1/en
Priority to CN201980063910.5A priority patent/CN113169305A/en
Priority to EP19898780.2A priority patent/EP3902032A4/en
Publication of WO2020129481A1 publication Critical patent/WO2020129481A1/en
Priority to US17/302,994 priority patent/US20210273256A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/14—Primary casings; Jackets or wrappings for protecting against damage caused by external factors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H01M50/174—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells
    • H01M50/178—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells for pouch or flexible bag cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/233—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by physical properties of casings or racks, e.g. dimensions
    • H01M50/238—Flexibility or foldability
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/552—Terminals characterised by their shape
    • H01M50/553—Terminals adapted for prismatic, pouch or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/116—Primary casings; Jackets or wrappings characterised by the material
    • H01M50/124—Primary casings; Jackets or wrappings characterised by the material having a layered structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a thin lithium secondary battery.
  • Japanese Unexamined Patent Application Publication No. 2016-139494 discloses a laminate type battery including a laminate member in which two films are stacked and a battery cell housed between the two films. There is. In the laminate type battery, the peripheral edge portion of the laminate member is folded in order to reduce the battery storage space in the device in which the laminate type battery is mounted.
  • both sides of the laminated outer body are bent by 90° for the purpose of improving space efficiency.
  • both sides of the laminated film are bent by 90° for the purpose of suppressing local deformation of the laminated film and suppressing insulation failure. ..
  • lithium secondary batteries also called lithium-ion secondary batteries
  • Known methods for manufacturing the smart card include a cold laminate in which a lithium secondary battery is sandwiched between card base materials and pressed at room temperature, and a hot laminate in which a lithium secondary battery is sandwiched between card base materials and heated and pressed. ing.
  • Japanese Unexamined Patent Publication No. 2005-74936 (Reference 4) relates to a method of manufacturing an IC card having an IC chip mounted instead of a thin battery. Also in the manufacture of an IC card, a step of sandwiching an IC chip between two base sheet and heating and pressing is performed.
  • the lithium secondary battery is pressed when the above-mentioned hot lamination is performed, and the electrolytic solution filled inside the battery is discharged to the outside of the battery. There is a risk of leakage.
  • the present invention is directed to a thin lithium secondary battery, and an object thereof is to suppress leakage of an electrolytic solution to the outside of the lithium secondary battery.
  • a lithium secondary battery is a positive electrode, a separator arranged on the positive electrode in a predetermined stacking direction, and a separator opposite to the positive electrode of the separator in the stacking direction.
  • the exterior body includes a rectangular coating region that overlaps the positive electrode, the separator, and the negative electrode in the stacking direction, and a rectangular frame-shaped outer peripheral region that surrounds the periphery of the coating region.
  • the outer peripheral region is a strip-shaped region that extends along a pair of sides other than the side on which the two terminals are arranged, and is a pair of first regions to which the two-layer sheet portions are joined and a pair of first regions.
  • a second region which is a strip-shaped region extending along at least one of the first region and the covering region, and in which the two-layer sheet portions are in contact with or close to each other in a non-bonded state. And This makes it possible to suppress the leakage of the electrolytic solution to the outside of the lithium secondary battery.
  • the positive electrode active material width which is the width of the positive electrode active material region in the width direction perpendicular to the pair of sides and the negative electrode active material width which is the width of the negative electrode active material region are different, the positive electrode The smaller one of the active material width and the negative electrode active material width is taken as a divisor, and when the positive electrode active material width and the negative electrode active material width are the same, one of the positive electrode active material width and the negative electrode active material width When one is a divisor, and the second region is present only between one of the pair of first regions and the covering region, the width of the second region is the dividend, and the pair of first regions When a pair of the second regions is present between both of the one region and the covering region, the total width of the pair of the second regions is taken as the dividend, and the value obtained by dividing the dividend by the divisor is 0.02. It is above 1 and below 1.
  • the at least one first region is folded back in the width direction by a folding line extending parallel to the pair of sides.
  • the folding line is located on the opposite side of the second region with respect to the center of the at least one first region in the width direction or the center of the at least one first region in the width direction.
  • the folding line is located between the widthwise center of the at least one first region and the second region.
  • the positive electrode includes a sheet-shaped current collector having conductivity and an active material plate which is a plate-shaped ceramic sintered body containing a lithium composite oxide.
  • the active material plate has a structure in which a plurality of primary particles having a layered rock salt structure are bonded.
  • the average inclination angle of the plurality of primary particles is greater than 0° and 30° or less.
  • the average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the active material plate.
  • the lithium secondary battery is used as a power supply source in a sheet-shaped device or a flexible device.
  • the lithium secondary battery is used as a power supply source in a smart card, which is the flexible device.
  • the lithium secondary battery is used as a power supply source in a target device that is subjected to a step of heating and pressurizing during manufacturing.
  • FIG. 3 is a cross-sectional view of a lithium secondary battery according to one embodiment. It is a top view of a lithium secondary battery. It is sectional drawing of another lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is a top view of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is sectional drawing of a lithium secondary battery. It is a figure which shows the flow of manufacture of a lithium secondary battery. It is a figure which shows the flow of manufacture of a lithium secondary battery. It is sectional drawing of a lithium secondary battery.
  • FIG. 1 is a sectional view showing the configuration of a lithium secondary battery 1 according to an embodiment of the present invention.
  • FIG. 2 is a plan view of the lithium secondary battery 1.
  • the lithium secondary battery 1 and its configuration are drawn thicker than they actually are.
  • a part of the structure on the front side and the back side of the cross section is also illustrated. The same applies to FIG.
  • the lithium secondary battery 1 is a small and thin battery.
  • the shape of the lithium secondary battery 1 in a plan view is, for example, a substantially rectangular shape.
  • the length of the lithium secondary battery 1 in the vertical direction in plan view is 10 mm to 46 mm
  • the length in the horizontal direction is 10 mm to 46 mm.
  • the thickness of the lithium secondary battery 1 (that is, the thickness in the vertical direction in FIG. 1) is, for example, 0.30 mm to 0.45 mm, preferably 0.40 mm to 0.45 mm.
  • the lithium secondary battery 1 is a sheet-shaped or flexible thin plate-shaped member.
  • the sheet-shaped member is a thin member that is easily deformed by a relatively small force, and is also called a film-shaped member. The same applies to the following description.
  • the lithium secondary battery 1 is mounted on, for example, a sheet-shaped device or a flexible device and used as a power supply source.
  • the sheet-like device is a thin device that is easily deformed by a relatively small force, and is also called a film-like device.
  • the lithium secondary battery 1 is, for example, built in a smart card having an arithmetic processing function and used as a power supply source in the smart card.
  • a smart card is a card-type flexible device.
  • the smart card is used as, for example, a card with a fingerprint authentication/wireless communication function including a wireless communication IC, a fingerprint analysis ASIC, and a fingerprint sensor.
  • a device for which the lithium secondary battery 1 is used as a power supply source such as a smart card, is also referred to as a “target device”.
  • the mounting of the lithium secondary battery 1 on the smart card is performed by, for example, cold lamination in which pressure is applied at room temperature or hot lamination in which pressure is applied while heating.
  • the processing temperature in hot lamination is, for example, 110°C to 260°C.
  • the upper limit of the processing temperature is preferably lower than 240°C, more preferably lower than 220°C, further preferably lower than 200°C, and most preferably 150°C or lower.
  • the processing pressure in hot lamination is, for example, 0.1 MPa (megapascal) to 6 MPa, and the processing time (that is, heating/pressurizing time) is, for example, 10 to 20 minutes.
  • the lithium secondary battery 1 includes a positive electrode 2, a negative electrode 3, a separator 4, an electrolytic solution 5, an outer casing 6, and two terminals 7.
  • the positive electrode 2, the separator 4, and the negative electrode 3 are stacked in a predetermined stacking direction.
  • the positive electrode 2, the separator 4, and the negative electrode 3 are stacked in the vertical direction in the figure.
  • the upper side and the lower side in FIG. 1 are simply referred to as “upper side” and “lower side”.
  • the up-down direction in FIG. 1 is simply referred to as “up-down direction” and also referred to as “overlapping direction”.
  • the vertical direction in FIG. 1 does not have to match the actual vertical direction when the lithium secondary battery 1 is mounted on a target device such as a smart card.
  • the separator 4 is arranged on the upper surface of the positive electrode 2 in the vertical direction (that is, the stacking direction).
  • the negative electrode 3 is arranged on the upper surface of the separator 4 in the vertical direction.
  • the negative electrode 3 is arranged on the side of the separator 4 opposite to the positive electrode 2 in the vertical direction.
  • Each of the positive electrode 2, the separator 4, and the negative electrode 3 has, for example, a substantially rectangular shape in a plan view.
  • the positive electrode 2, the separator 4, and the negative electrode 3 have approximately the same shape in plan view (that is, approximately the same shape and approximately the same size).
  • the exterior body 6 is a sheet-shaped and bag-shaped member.
  • the exterior body 6 is substantially rectangular in plan view.
  • the exterior body 6 includes two layers of sheet portions 65 and 66 that are vertically overlapped with each other.
  • first sheet portion 65 the sheet portion 65 located below the positive electrode 2
  • second sheet portion 66 the sheet portion 66 located above the negative electrode 3
  • the outer peripheral edge of the first sheet portion 65 and the outer peripheral edge of the second sheet portion 66 are joined by, for example, heat fusion (so-called heat sealing).
  • the first sheet portion 65 and the second sheet portion 66 of the outer package 6 are each made of, for example, a laminated film in which a metal foil 61 formed of a metal such as aluminum (Al) and an insulating resin layer 62 are laminated. It is formed. In the first sheet portion 65 and the second sheet portion 66, the resin layer 62 is located inside the metal foil 61.
  • the exterior body 6 covers the positive electrode 2 and the negative electrode 3 from both sides in the vertical direction.
  • the outer package 6 houses the positive electrode 2, the separator 4, the negative electrode 3, and the electrolytic solution 5 therein.
  • the electrolytic solution 5 continuously exists around the positive electrode 2, the separator 4, and the negative electrode 3. In other words, the electrolytic solution 5 is interposed between the positive electrode 2 and the negative electrode 3.
  • the electrolytic solution 5 impregnates the positive electrode 2, the separator 4, and the negative electrode 3.
  • the two terminals 7 extend from the inside of the exterior body 6 to the outside. Inside the outer package 6, one terminal 7 is electrically connected to the positive electrode 2, and the other terminal 7 is electrically connected to the negative electrode 3.
  • the positive electrode 2 includes a positive electrode current collector 21, a positive electrode active material plate 22, and a conductive bonding layer 23.
  • the positive electrode current collector 21 is a conductive sheet-shaped member.
  • the lower surface of the positive electrode current collector 21 is bonded to the resin layer 62 of the exterior body 6 via the positive electrode bonding layer 63.
  • the positive electrode bonding layer 63 is formed of, for example, a mixed resin of acid-modified polyolefin-based resin and epoxy-based resin.
  • the positive electrode bonding layer 63 may be formed of various other materials.
  • the thickness of the positive electrode bonding layer 63 is, for example, 0.5 ⁇ m to 10 ⁇ m.
  • the positive electrode current collector 21 includes, for example, a metal foil formed of a metal such as aluminum and a conductive carbon layer laminated on the upper surface of the metal foil.
  • a metal foil formed of a metal such as aluminum and a conductive carbon layer laminated on the upper surface of the metal foil.
  • the main surface of the positive electrode current collector 21 facing the positive electrode active material plate 22 is covered with the conductive carbon layer.
  • the metal foil described above is formed of various metals other than aluminum (for example, copper, nickel, silver, gold, chromium, iron, tin, lead, tungsten, molybdenum, titanium, zinc, or alloys containing these). May be.
  • the conductive carbon layer may be omitted from the positive electrode current collector 21.
  • the positive electrode active material plate 22 (that is, the active material plate of the positive electrode 2) is a relatively thin plate-shaped ceramic sintered body containing a lithium composite oxide.
  • the positive electrode active material plate 22 is bonded onto the upper surface of the positive electrode current collector 21 via the conductive bonding layer 23.
  • the positive electrode active material plate 22 faces the separator 4 in the vertical direction.
  • the upper surface of the positive electrode active material plate 22 contacts the lower surface of the separator 4.
  • the positive electrode active material plate 22 contains substantially no resin. Therefore, the main surface of the positive electrode 2 facing the separator 4 (that is, the upper surface in FIG. 1) contains substantially no resin.
  • the positive electrode active material plate 22 has a structure in which a plurality of (that is, a large number of) primary particles are bonded.
  • the primary particles are composed of a lithium composite oxide having a layered rock salt structure.
  • the lithium composite oxide is typically an oxide represented by the general formula: Li p MO 2 (wherein 0.05 ⁇ p ⁇ 1.10).
  • M is at least one kind of transition metal, and includes, for example, one or more kinds selected from cobalt (Co), nickel (Ni) and manganese (Mn).
  • the layered rock salt structure is a crystal structure in which lithium layers and transition metal layers other than lithium are alternately stacked with an oxygen layer in between.
  • the layered rock salt structure has a crystal structure in which transition metal ion layers and lithium single layers are alternately stacked via oxide ions (typically, ⁇ -NaFeO 2 type structure: cubic rock salt type structure [111 ] A structure in which a transition metal and lithium are regularly arranged in the axial direction).
  • the lithium composite oxide is lithium cobalt oxide (L
  • the positive electrode active material plate 22 includes magnesium (Mg), aluminum, silicon (Si), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu). , Zinc (Zn), gallium (Ga), germanium (Ge), strontium (Sr), yttrium (Y), zirconia (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), tin (Sn). , Antimony (Sb), tellurium (Te), barium (Ba), bismuth (Bi), and the like may be further included in one or more kinds. In addition, the positive electrode active material plate 22 may be sputtered with gold (Au) or the like as a current collecting aid.
  • Au gold
  • the average primary particle size of the plurality of primary particles is, for example, 20 ⁇ m or less, preferably 15 ⁇ m or less.
  • the primary particle size is, for example, 0.2 ⁇ m or more, preferably 0.4 ⁇ m or more.
  • the primary particle size can be measured by analyzing an SEM (scanning electron microscope) image of the cross section of the positive electrode active material plate 22.
  • the positive electrode active material plate 22 is processed by a cross section polisher (CP) to expose a polished cross section, and the polished cross section is subjected to a predetermined magnification (for example, 1000 times) and a predetermined visual field (for example, 125 ⁇ m). ⁇ 125 ⁇ m) and observed by SEM.
  • CP cross section polisher
  • the visual field is set so that 20 or more primary particles are present in the visual field.
  • the diameter of the circumscribed circle when the circumscribed circle is drawn for all the primary particles in the obtained SEM image is determined, and the average value of these is taken as the primary particle size.
  • the average tilt angle (that is, the average orientation angle) of the plurality of primary particles is preferably larger than 0° and 30° or less.
  • the average tilt angle is more preferably 5° or more and 28° or less, and further preferably 10° or more and 25° or less.
  • the average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the positive electrode active material plate 22 (for example, the lower surface of the positive electrode active material plate 22).
  • the tilt angle of the primary particles was analyzed by electron beam backscattering diffraction (EBSD) on the cross section of the positive electrode active material plate 22. It can be measured by Specifically, for example, the positive electrode active material plate 22 is processed by a cross section polisher to expose a polished cross section, and the polished cross section has a predetermined magnification (for example, 1000 times) and a predetermined visual field (for example, 125 ⁇ m ⁇ 125 ⁇ m). Analyze by EBSD at. In the obtained EBSD image, the tilt angle of each primary particle is represented by the shade of color, and the darker the color, the smaller the tilt angle. Then, the average value of the inclination angles of the plurality of primary particles obtained from the EBSD image is set as the above-mentioned average inclination angle.
  • EBSD electron beam backscattering diffraction
  • the proportion of the primary particles having a tilt angle of more than 0° and 30° or less is preferably 60% or more, more preferably 80% or more, More preferably, it is 90% or more.
  • the upper limit of the ratio is not particularly limited and may be 100%.
  • the ratio can be obtained by obtaining the total area of the primary particles having an inclination angle larger than 0° and 30° or less in the above EBSD image and dividing the total area of the primary particles by the total particle area. it can.
  • the porosity of the positive electrode active material plate 22 is, for example, 25% to 45%.
  • the porosity of the positive electrode active material plate 22 is a volume ratio of pores (including open pores and closed pores) in the positive electrode active material plate 22.
  • the porosity can be measured by analyzing a SEM image of the cross section of the positive electrode active material plate 22.
  • the positive electrode active material plate 22 is processed by a cross section polisher (CP) to expose a polished cross section.
  • the polished cross section is observed by SEM with a predetermined magnification (for example, 1000 times) and a predetermined visual field (for example, 125 ⁇ m ⁇ 125 ⁇ m).
  • the obtained SEM image is analyzed, the area of all pores in the visual field is divided by the area (cross-sectional area) of the positive electrode active material plate 22 in the visual field, and the obtained value is multiplied by 100 to obtain the porosity ( %).
  • the average pore diameter which is the average value of the diameter of the pores included in the positive electrode active material plate 22, is, for example, 15 ⁇ m or less, preferably 12 ⁇ m or less, and more preferably 10 ⁇ m or less.
  • the average pore diameter is, for example, 0.1 ⁇ m or more, preferably 0.3 ⁇ m or more.
  • the diameter of the pores described above is typically the diameter of the sphere when the pores are assumed to be spherical with the same volume or the same cross-sectional area.
  • the average pore diameter is an average value of the diameters of a plurality of pores calculated on a number basis.
  • the average pore diameter can be obtained by a known method such as analysis of a cross-sectional SEM image or mercury porosimetry.
  • the average pore diameter is measured by a mercury porosimetry method using a mercury porosimeter.
  • the positive electrode active material plate 22 is a single plate-shaped member, but it may be divided into a plurality of plate-shaped members (hereinafter referred to as “active material plate elements”).
  • each of the plurality of active material plate elements is bonded to the positive electrode current collector 21 via the conductive bonding layer 23.
  • the plurality of active material plate elements are arranged in a matrix (that is, a grid) on the positive electrode current collector 21, for example.
  • the shape of each active material plate element in a plan view is, for example, a substantially rectangular shape.
  • the plurality of active material plate elements may have substantially the same shape (that is, substantially the same shape and substantially the same size) in plan view, or may have different shapes.
  • the plurality of active material plate elements are arranged apart from each other in a plan view.
  • the conductive bonding layer 23 contains conductive powder and a binder.
  • the conductive powder is, for example, powder of acetylene black, scaly natural graphite, carbon nanotubes, carbon nanofibers, carbon nanotube derivatives, or carbon nanofiber derivatives.
  • the binder includes, for example, a polyimide amide resin.
  • the polyimide amide resin contained in the binder may be one type or two or more types. Further, the binder may contain a resin other than the polyimide amide resin.
  • the conductive bonding layer 23 is formed by coating the positive electrode current collector 21 or the positive electrode active material plate 22 with a liquid or paste adhesive containing the above-described conductive powder and binder, and a solvent. And the positive electrode active material plate 22 are formed by evaporating and solidifying the solvent.
  • the thickness of the positive electrode current collector 21 is, for example, 9 ⁇ m to 50 ⁇ m, preferably 9 ⁇ m to 20 ⁇ m, and more preferably 9 ⁇ m to 15 ⁇ m.
  • the thickness of the positive electrode active material plate 22 is, for example, 15 ⁇ m to 200 ⁇ m, preferably 30 ⁇ m to 150 ⁇ m, and more preferably 50 ⁇ m to 100 ⁇ m. By thickening the positive electrode active material plate 22, the active material capacity per unit area can be increased and the energy density of the lithium secondary battery 1 can be increased. By thinning the positive electrode active material plate 22, it is possible to suppress deterioration of battery characteristics (in particular, increase in resistance value) due to repeated charging and discharging.
  • the thickness of the conductive bonding layer 23 is, for example, 3 ⁇ m to 28 ⁇ m, preferably 5 ⁇ m to 25 ⁇ m.
  • the negative electrode 3 includes a negative electrode current collector 31 and a negative electrode active material layer 32.
  • the negative electrode current collector 31 is a conductive sheet-shaped member.
  • the upper surface of the negative electrode current collector 31 is bonded to the exterior body 6 via the negative electrode bonding layer 64.
  • the negative electrode bonding layer 64 is formed of, for example, a mixed resin of acid-modified polyolefin resin and epoxy resin.
  • the negative electrode bonding layer 64 may be formed of various other materials.
  • the thickness of the negative electrode bonding layer 64 is, for example, 0.5 ⁇ m to 10 ⁇ m.
  • the negative electrode current collector 31 is, for example, a metal foil formed of a metal such as copper.
  • the metal foil is various metals other than copper (for example, copper, stainless steel, nickel, aluminum, silver, gold, chromium, iron, tin, lead, tungsten, molybdenum, titanium, zinc, or alloys containing these, etc.). ).
  • the negative electrode active material layer 32 includes a binder containing a resin as a main component and a carbonaceous material that is a negative electrode active material.
  • the negative electrode active material layer 32 is coated on the lower surface of the negative electrode current collector 31. That is, the negative electrode 3 is a so-called coated electrode.
  • the negative electrode active material layer 32 faces the separator 4 in the vertical direction.
  • the lower surface of the negative electrode active material layer 32 contacts the upper surface of the separator 4.
  • the above-mentioned carbonaceous material is, for example, graphite (natural graphite or artificial graphite), pyrolytic carbon, coke, resin fired body, mesophase spherule, or mesophase pitch.
  • a lithium storage material may be used as the negative electrode active material instead of the carbonaceous material.
  • the lithium storage material is, for example, silicon, aluminum, tin, iron, iridium, or an alloy, oxide, or fluoride containing these.
  • the binder is, for example, styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF) or a mixture thereof.
  • SBR is used as a binder.
  • SBR is less likely to dissolve in ⁇ -butyrolactone (GBL) contained in the electrolytic solution 5 described later. Therefore, by using SBR as the binder of the negative electrode 3, the deterioration of the negative electrode active material layer 32 due to the electrolytic solution 5 can be suppressed.
  • the thickness of the negative electrode current collector 31 is, for example, 5 ⁇ m to 25 ⁇ m, preferably 8 ⁇ m to 20 ⁇ m, and more preferably 8 ⁇ m to 15 ⁇ m.
  • the thickness of the negative electrode active material layer 32 is, for example, 20 ⁇ m to 300 ⁇ m, preferably 30 ⁇ m to 250 ⁇ m, and more preferably 30 ⁇ m to 150 ⁇ m.
  • the lithium secondary battery 1 may be provided with a negative electrode 3a having a structure different from that of the negative electrode 3, as shown in FIG. 3, instead of the negative electrode 3 which is a coating electrode.
  • the negative electrode 3a has substantially the same structure as the positive electrode 2 described above.
  • the negative electrode 3a includes a negative electrode current collector 31a, a negative electrode active material plate 32a, and a conductive bonding layer 33a.
  • the negative electrode current collector 31a is a sheet-shaped member having conductivity.
  • the negative electrode current collector 31a is, for example, a member having the same structure and made of the same material as the negative electrode current collector 31 described above.
  • the negative electrode active material plate 32a (that is, the active material plate of the negative electrode 3a) is a relatively thin plate-shaped ceramic sintered body containing a lithium composite oxide (for example, lithium titanium oxide (LTO)).
  • the negative electrode active material plate 32a is bonded to the lower surface of the negative electrode current collector 31a via the conductive bonding layer 33a.
  • the conductive bonding layer 33a is formed of, for example, the same material as the conductive bonding layer 23 of the positive electrode 2 described above.
  • the negative electrode active material plate 32a faces the separator 4 in the vertical direction.
  • the lower surface of the negative electrode active material plate 32 a contacts the upper surface of the separator 4.
  • the negative electrode active material plate 32 a like the positive electrode active material plate 22, contains substantially no resin. Therefore, the main surface of the negative electrode 3a facing the separator 4 (that is, the lower surface in FIG. 3) contains substantially no resin.
  • the thickness of the negative electrode current collector 31 is, for example, 5 ⁇ m to 25 ⁇ m, preferably 8 ⁇ m to 20 ⁇ m, and more preferably 8 ⁇ m to 15 ⁇ m.
  • the thickness of the negative electrode active material plate 32a is, for example, 10 ⁇ m to 300 ⁇ m, preferably 30 ⁇ m to 200 ⁇ m, and more preferably 30 ⁇ m to 150 ⁇ m. By thickening the negative electrode active material plate 32a, the active material capacity per unit area can be increased and the energy density of the lithium secondary battery 1 can be increased. By thinning the negative electrode active material plate 32a, it is possible to suppress deterioration of battery characteristics (in particular, increase in resistance value) due to repeated charging and discharging.
  • the thickness of the conductive bonding layer 33a is, for example, 3 ⁇ m to 30 ⁇ m, preferably 5 ⁇ m to 25 ⁇ m.
  • the negative electrode active material plate 32a is a single plate-shaped member, but may be divided into a plurality of plate-shaped members (hereinafter referred to as “active material plate elements”).
  • each of the plurality of active material plate elements is bonded to the negative electrode current collector 31a via the conductive bonding layer 33a.
  • the plurality of active material plate elements are arranged in a matrix (that is, a grid) on the negative electrode current collector 31a.
  • the shape of each active material plate element in a plan view is, for example, a substantially rectangular shape.
  • the plurality of active material plate elements may have substantially the same shape (that is, substantially the same shape and substantially the same size) in plan view, or may have different shapes.
  • the plurality of active material plate elements are arranged apart from each other in a plan view.
  • the electrolytic solution 5 is, for example, a solution in which lithium borofluoride (LiBF 4 ) is dissolved in a non-aqueous solvent.
  • the non-aqueous solvent may be a single solvent consisting of ⁇ -butyrolactone (GBL) or a mixed solvent containing GBL and ethylene carbonate (EC).
  • GBL ⁇ -butyrolactone
  • EC ethylene carbonate
  • the volume ratio of EC:GBL in the non-aqueous solvent is, for example, 0:1 to 1:1 (that is, the GBL ratio is 50% to 100% by volume). , Preferably 0:1 to 1:1.5 (GBL ratio 60% by volume to 100% by volume), and more preferably 0:1 to 1:2 (GBL ratio 66.6% by volume to 100% by volume). And more preferably 0:1 to 1:3 (GBL ratio 75% to 100% by volume).
  • the solvent of the electrolytic solution 5 may be changed variously.
  • the solvent of the electrolytic solution 5 does not necessarily need to contain GBL and may be a single solvent of EC.
  • LiBF 4 which is a solute, is an electrolyte having a high decomposition temperature. Therefore, the heat resistance of the lithium secondary battery 1 can be further improved.
  • the LiBF 4 concentration in the electrolytic solution 5 is, for example, 0.5 mol/L to 2 mol/L, preferably 0.6 mol/L to 1.9 mol/L, and more preferably 0.7 mol/L to 1.7 mol. /L, and more preferably 0.8 mol/L to 1.5 mol/L.
  • the solute of the electrolytic solution 5 may be variously changed.
  • the solute of the electrolytic solution 5 may be lithium hexafluorophosphate (LiPF 6 ).
  • the electrolytic solution 5 preferably further contains vinylene carbonate (VC) and/or fluoroethylene carbonate (FEC) as an additive. Both VC and FEC have excellent heat resistance. When the electrolytic solution 5 contains the additive, a SEI film having excellent heat resistance is formed on the surface of the negative electrode 3, and the heat resistance of the lithium secondary battery 1 can be further improved.
  • VC vinylene carbonate
  • FEC fluoroethylene carbonate
  • the separator 4 is a sheet-shaped or thin plate-shaped insulating member.
  • the separator 4 is, for example, a single-layer separator made of resin.
  • the resin is, for example, polyimide, polyethylene, polyester (for example, polyethylene terephthalate (PET)), polypropylene, or the like.
  • the separator 4 is a polyimide porous film (for example, a three-dimensional porous structure (3DOM)).
  • Polyimide is superior in heat resistance to polyethylene and polypropylene, and is also excellent in wettability with GBL. Therefore, the heat resistance of the lithium secondary battery 1 can be improved by using the separator 4 made of polyimide. Further, the electrolytic solution 5 can be prevented from being repelled by the separator 4, and the electrolytic solution 5 can easily permeate into the separator 4.
  • the separator 4 may be, for example, a two-layer separator in which a resin layer is laminated on a ceramic substrate.
  • the separator 4 may be a two-layer separator in which a substrate, which is a resin layer, is coated with ceramic.
  • the separator 4 may have a multilayer structure of three layers or more.
  • the separator 4 may be a three-layer separator in which resin layers are laminated on the upper surface and the lower surface of the ceramic substrate.
  • FIG. 4 is a cross-sectional view of the lithium secondary battery 1 taken along the line IV-IV in FIG.
  • FIG. 5 is an enlarged view showing the left end portion of the lithium secondary battery 1 in FIG.
  • the lithium secondary battery 1 and its configuration are drawn thicker than they actually are in order to facilitate understanding of the drawings.
  • the exterior body 6 the detailed illustration of the laminated structure is omitted, and it is drawn by one solid line.
  • FIG. 6 is a plan view of the lithium secondary battery 1.
  • the outer casing 6 includes a covering region 67 and an outer peripheral region 68.
  • the outer peripheral area 68 includes a first area 681 and a second area 682.
  • the outer peripheral area 68 includes two first areas 681 and two second areas 682.
  • the covering region 67, the first region 681, and the second region 682 are each surrounded by a chain double-dashed line.
  • the hatched area 67 and the area of the outer peripheral area 68 excluding the second area 682 are hatched in parallel.
  • the second area 682 of the outer peripheral area 68 is not shaded with parallel diagonal lines.
  • the covering region 67 of the outer package 6 is a substantially rectangular region that vertically overlaps the positive electrode 2, the separator 4, and the negative electrode 3 in a plan view.
  • the outer peripheral region 68 is a region (that is, a region that does not overlap the positive electrode 2, the separator 4, and the negative electrode 3) of the exterior body 6 excluding the coating region 67, and has a substantially rectangular frame shape surrounding the periphery of the coating region 67 in plan view. Area.
  • the outer peripheral area 68 is continuous with the covered area 67.
  • the two first regions 681 are substantially rectangular strip-shaped regions that extend along a pair of sides on both sides in the left-right direction in FIGS. 4 and 6 (hereinafter, also referred to as “long sides 691”).
  • the left-right direction in FIGS. 4 to 6 is also referred to as “width direction”.
  • the width direction is substantially perpendicular to the pair of long sides 691 of the exterior body 6.
  • Each first region 681 is a region including a long side 691, and is separated in the width direction from a pair of sides in the width direction of the covering region 67.
  • the two-layer sheet portions that is, the first sheet portion 65 and the second sheet portion 66 of the exterior body 6 that overlap in the vertical direction are joined as described above.
  • each first region 681 in the direction perpendicular to the width direction is substantially the same as the length of the covered region 67 in the longitudinal direction. ..
  • the width of each first region 681 in the width direction (hereinafter, also simply referred to as “width”) is substantially constant over the entire length in the longitudinal direction.
  • the width of the first region 681 is, for example, 1 mm to 5 mm, preferably 1.5 mm to 4 mm, and more preferably 2 mm to 3 mm.
  • the first region 681 only needs to have a shape that can be regarded as a substantially strip shape, and the width of the first region 681 may change slightly in the longitudinal direction.
  • the two second regions 682 are arranged between the covering region 67 and the pair of first regions 681 on both sides of the covering region 67 in the width direction.
  • the two second regions 682 are substantially rectangular strip-shaped regions extending in the longitudinal direction along a pair of sides of the covering region 67 in the width direction.
  • the two second regions 682 are substantially rectangular strip-shaped regions extending in the longitudinal direction along the pair of first regions 681.
  • Each second region 682 is continuous with the covering region 67 and the first region 681 in the width direction.
  • the two-layer sheet portions (that is, the first sheet portion 65 and the second sheet portion 66) of the exterior body 6 that are vertically overlapped are in contact with each other in a non-bonded state.
  • the contact is a direct contact in which the electrolytic solution 5 and the like are not interposed between the first sheet portion 65 and the second sheet portion 66.
  • the first sheet portion 65 and the second sheet portion 66 may be close to each other with a slight gap therebetween.
  • the electrolyte solution 5 may be slightly present in the void, or the electrolyte solution 5 may not be present.
  • each second region 682 in the longitudinal direction is substantially the same as the length of the covering region 67 and the first region 681 in the longitudinal direction.
  • the width of each second region 682 in the width direction is substantially constant over the entire length in the longitudinal direction.
  • the width of the second region 682 is, for example, 0.3 mm to 25 mm, preferably 0.5 mm to 15 mm, and more preferably 1 mm to 5 mm.
  • the second region 682 only needs to have a shape that can be regarded as a substantially strip shape, and the width of the second region 682 may change slightly in the longitudinal direction.
  • the total width of the pair of second areas 682 arranged in the width direction is referred to as “second area width A1”.
  • the width of the positive electrode active material plate 22 of the positive electrode 2 (that is, the width of the active material region in which the active material is provided in the positive electrode 2) is referred to as the “positive electrode active material width”
  • the width of the negative electrode active material layer 32 of the negative electrode 3 ( That is, the width of the active material region in which the active material is provided in the negative electrode 3) is called the “negative electrode active material width”.
  • the positive electrode active material width and the negative electrode active material width are different, the smaller width of the positive electrode active material width and the negative electrode active material width is referred to as “active material region width B3”.
  • the positive electrode active material width and the negative electrode active material width are the same, one of the positive electrode active material width and the negative electrode active material width is set as the active material region width B3.
  • the width of the positive electrode active material plate 22 is substantially the same as the width of the negative electrode active material layer 32.
  • the active material region width B3 may be either the positive electrode active material width or the negative electrode active material width.
  • a value obtained by dividing the dividend by the divisor with the second region width A1 as the dividend and the active material region width B3 as the divisor is, for example, 0.02 or more, It is preferably 0.04 or more.
  • the second region width A1/active material region width B3 is, for example, 1 or less, preferably 0.2 or less.
  • the active material region width B3 is, for example, 15 mm to 25 mm.
  • the second regions 682 do not necessarily have to be provided on both sides of the covering region 67 in the width direction, and may be arranged only on one side of the covering region 67 in the width direction. In other words, the second region 682 may be provided between at least one of the pair of first regions 681 and the covering region 67.
  • the above-mentioned second region width A1 is the same as the one of the first region 681. This is the width of the two areas 682.
  • the first region 681 and the second region 682 extend substantially parallel to the width direction at both ends of the exterior body 6 in the width direction, but the shape of the first region 681 is It may be changed in various ways.
  • the first region 681 of the exterior body 6 has a fold line 693 extending in parallel to the pair of long sides 691 (see FIG. 6) of the exterior body 6 in the width direction inside ( That is, it is folded back by about 180° to the side closer to the covering region 67).
  • non-folding part 694 a part of the outer peripheral region 68 extending from the covering region 67 to the folding line 693
  • folding part 695 a part folded back inward in the width direction at the folding line 693
  • the folded portion 695 faces the non-folded portion 694 in the vertical direction.
  • the folded portion 695 is folded back to the upper side (that is, the negative electrode 3 side) in the drawings, but is folded back to the lower side (that is, the positive electrode 2 side) in the drawings.
  • the first region 681 and the second region 682 on one side in the width direction are shown, but the first region 681 and the second region 682 on the other side in the width direction also have the same structure. May have.
  • the folding line 693 is located in the outer peripheral region 68 at substantially the center of the first region 681 in the width direction. Therefore, the edge of the folded-back portion 695 (that is, the side edge opposite to the folded-back line 693) is located at substantially the same position in the width direction as the boundary between the first region 681 and the second region 682 in the non-folded-back portion 694.
  • the first region 681 is folded in half along the folding line 693, and the folded-back portion 695 of the first region 681 vertically faces the remaining portion of the first region 681. Further, the folded portion 695 of the first region 681 does not face the second region 682 in the vertical direction.
  • the second region 682 is located between the folding line 693 and the covering region 67, and thus is not folded back. In other words, the folded portion 695 does not include the second region 682.
  • the folding line 693 is located in the outer peripheral region 68 on the opposite side of the second region 682 with respect to the center of the first region 681 in the width direction (that is, outside the center in the width direction). .. Therefore, the edge of the folded portion 695 is located on the outer side in the width direction (that is, the side farther from the covering region 67) than the boundary between the first region 681 and the second region 682 in the non-folded portion 694.
  • the first region 681 is folded in half along the folding line 693, and the folded-back portion 695 of the first region 681 vertically faces the remaining portion of the first region 681.
  • the folded portion 695 of the first region 681 does not face the second region 682 in the vertical direction.
  • the second region 682 is located between the folding line 693 and the covering region 67, and thus is not folded back. In other words, the folded portion 695 does not include the second region 682.
  • the fold line 693 is located in the outer peripheral region 68 between the widthwise center of the first region 681 and the second region 682. Therefore, the edge of the folded portion 695 is located on the inner side in the width direction (that is, on the side closer to the covered region 67) than the boundary between the first region 681 and the second region 682 in the non-folded portion 694.
  • the first region 681 is folded in two along the folding line 693, and the folded portion 695 of the first region 681 vertically faces the remaining portion of the first region 681 and the second region 682.
  • the folded portion 695 opposes substantially the entire non-folded portion 694 in the vertical direction.
  • the second region 682 is located between the folding line 693 and the covering region 67, and thus is not folded back. In other words, the folded portion 695 does not include the second region 682.
  • the first sheet portion 65 and the second sheet portion 66 of the exterior body 6 two aluminum laminated films (manufactured by Showa Denko Packaging, thickness 61 ⁇ m, three-layer structure of polypropylene film/aluminum foil/nylon film) Be prepared. Further, the positive electrode active material plate 22 is prepared. The positive electrode active material plate 22 is formed by sintering a LiCoO 2 green sheet. In the example shown in FIG. 10A, the positive electrode active material plate 22 has a plurality of active material plate elements 24. Even when the positive electrode active material plate 22 is a continuous member (that is, a single plate), the following manufacturing method is substantially the same.
  • the LiCoO 2 green sheet is manufactured as follows. First, Co 3 O 4 powder (manufactured by Shodo Chemical Industry Co., Ltd.) and Li 2 CO 3 powder (manufactured by Honjo Chemical Co., Ltd.), which were weighed so that the molar ratio of Li/Co was 1.01, were mixed. After that, it is held at 780° C. for 5 hours. Subsequently, the obtained powder is crushed and crushed in a pot mill so that the volume-based D50 is 0.4 ⁇ m, and a powder composed of LiCoO 2 plate-like particles is obtained.
  • binder polyvinyl butyral: product number BM-2, manufactured by Sekisui Chemical Co., Ltd.
  • plastic 4 parts by weight of the agent DOP: Di(2-ethylhexyl) phthalate, manufactured by Kurogane
  • the obtained mixture is stirred under reduced pressure for defoaming, and the viscosity is adjusted to 4000 cP to prepare a LiCoO 2 slurry.
  • the viscosity is measured by a Brookfield LVT viscometer.
  • the slurry thus prepared is formed into a sheet on a polyethylene terephthalate (PET) film by a doctor blade method to form a LiCoO 2 green sheet.
  • the thickness of the LiCoO 2 green sheet after drying was 98 ⁇ m.
  • the LiCoO 2 green sheet peeled from the PET film is cut into 50 mm square with a cutter, and placed on the center of a magnesia setter (size 90 mm square, height 1 mm) as a lower setter. Further, a porous magnesia setter as an upper setter is placed on the LiCoO 2 sheet.
  • the LiCoO 2 sheet is placed in a 120 mm square alumina sheath (manufactured by Nikkato Co., Ltd.) while being sandwiched between setters. At this time, the lid is opened with a gap of 0.5 mm without sealing the alumina sheath.
  • the obtained laminate is heated to 600° C.
  • LiCoO 2 sintered body plate having a thickness of 90 ⁇ m is obtained.
  • the obtained LiCoO 2 sintered body plate is cut into a rectangular shape of 10.5 mm ⁇ 9.5 mm square by a laser processing machine to obtain a plurality of active material plate elements 24 (that is, the positive electrode active material plate 22). ..
  • the positive electrode active material plate 22 When the positive electrode active material plate 22 is prepared, acetylene black is mixed with a solution in which polyamideimide (PAI) is dissolved in N-methylpyrrolidone to prepare a slurry, and 2 ⁇ L (microliter) of the slurry is used as a positive electrode current collector.
  • the conductive bonding layer 23 is formed by being dropped on the body 21 (aluminum foil having a thickness of 9 mm). Then, the positive electrode active material plate 22 is placed on the conductive bonding layer 23 and dried. In the example shown in FIG. 10A, the positive electrode active material plate 22 having the plurality of active material plate elements 24 is bonded to the positive electrode current collector 21 via the conductive bonding layer 23.
  • PAI polyamideimide
  • the composite body of the positive electrode current collector 21 and the positive electrode active material plate 22 (that is, the plurality of active material plate elements 24) is laminated on the first sheet portion 65, and the first sheet portion is interposed via the positive electrode bonding layer 63.
  • the positive electrode assembly 20 is formed by being bonded to 65.
  • One end of one terminal 7 is fixed to the positive electrode current collector 21 in advance by welding.
  • the negative electrode active material layer 32 (carbon layer having a thickness of 130 ⁇ m) is coated on the negative electrode current collector 31 (copper foil having a thickness of 10 ⁇ m).
  • the negative electrode active material layer 32 is a carbon coating film containing a mixture of graphite as an active material and PVDF as a binder.
  • the composite body of the negative electrode current collector 31 and the negative electrode active material layer 32 is laminated on the second sheet portion 66 and bonded to the second sheet portion 66 via the negative electrode bonding layer 64, whereby the negative electrode assembly is formed.
  • a product 30 is formed. Note that one end of one terminal 7 is fixed to the negative electrode current collector 31 in advance by welding.
  • a porous polyimide film (TOKS-8023i2 manufactured by Tokyo Ohka Kogyo) is prepared. Then, the positive electrode assembly 20, the separator 4, and the negative electrode assembly 30 are sequentially laminated so that the positive electrode active material plate 22 and the negative electrode active material layer 32 face the separator 4, and the intermediate laminate 10 is formed. In the intermediate laminate 10, both upper and lower surfaces are covered with the exterior body 6 (that is, the first sheet portion 65 and the second sheet portion 66), and the first positive electrode assembly 20, the separator 4, and the negative electrode assembly 30 are surrounded by a first The seat portion 65 and the second seat portion 66 extend.
  • the exterior body 6 that is, the first sheet portion 65 and the second sheet portion 66
  • the thickness of the positive electrode assembly 20, the separator 4, and the negative electrode assembly 30 (hereinafter collectively referred to as “battery element”) in the vertical direction is 0.33 mm.
  • the shape of the battery element in plan view is a substantially rectangular shape of 2.3 cm ⁇ 3.2 cm.
  • three of the four sides of the substantially rectangular intermediate laminate 10 are sealed by heat fusion bonding.
  • three sides are sealed except one side on the upper side in the figure.
  • the three sides include one side from which the two terminals 7 project.
  • a patch jig adjusted to have a sealing width of 2 mm is used, and the outer peripheral portion of the intermediate laminate 10 is heated at 200° C. and 1.5 MPa (megapascal) for 10 seconds. And pressurized.
  • the first sheet The portion 65 and the second sheet portion 66 are heat-sealed.
  • the intermediate laminate 10 is housed in the vacuum dryer 81 to remove moisture and dry the adhesive (that is, the positive electrode bonding layer 63, the negative electrode bonding layer 64, and the conductive bonding layer 23). Is done. At this time, the gas existing between the second regions 682 is removed on one sealed side located on the lower side in the drawing. As a result, in the second region 682, the first sheet portion 65 and the second sheet portion 66 are in contact with each other in the non-contact state, or are close to each other with a slight gap therebetween.
  • the adhesive that is, the positive electrode bonding layer 63, the negative electrode bonding layer 64, and the conductive bonding layer 23.
  • the intermediate laminate 10 is housed in the glove box 82.
  • the injection device 83 is inserted between the first sheet portion 65 and the second sheet portion 66, and the electrolytic solution 5 receives the electrolytic solution 5 via the injection device 83.
  • the electrolyte solution 5 was prepared by dissolving LiBF 4 in a mixed solvent containing EC and GBL in a volume ratio of 1:3 so as to have a concentration of 1.5 mol/L, and further adding 5% by weight of VC as an additive. It is a liquid added so that.
  • the unsealed one side is temporarily sealed (that is, vacuum-sealed) in the glove box 82 under a depressurized atmosphere with an absolute pressure of 5 kPa. Then, the intermediate laminate 10 is subjected to initial charging and aging for 7 days. When the aging ends, a portion of the first sheet portion 65 and the second sheet portion 66 near the outer edge of one temporarily sealed side (that is, the end portion that does not include the battery element) is cut off and generated by the aging. The gas containing the water and the like is removed (that is, degassing is performed).
  • the sides formed by the above cutting are sealed by heat fusion bonding in a depressurized atmosphere in the glove box 82 with an absolute pressure of 5 kPa.
  • the patch jig adjusted so that the sealing width might be 2 mm was used similarly to the above-mentioned three sides sealing, and the 1st sheet part 65 and the 2nd sheet part 66 are 200 degreeC. , And heated and pressurized at 1.5 MPa for 10 seconds.
  • the outer peripheral region 68 see FIG. 6) of the exterior body 6, in the first region 681 on one side located on the upper side in the drawing, the first sheet portion 65 and the second sheet portion 66 are heated.
  • the lithium secondary battery 1 is formed. Further, in the second region 682 of the one side located on the upper side in the drawing, the first sheet portion 65 and the second sheet portion 66 are in contact with each other in a non-contact state, or are close to each other with a slight gap therebetween. .. After that, an extra portion of the outer peripheral portion of the outer package 6 is cut off, and the shape of the lithium secondary battery 1 is adjusted. When the lithium secondary battery 1 illustrated in FIGS. 7 to 9 is manufactured, the folded-back portion 695 of the outer package 6 is folded back along the folded-back line 693.
  • the shape of the lithium secondary battery 1 in plan view was a rectangle of 38 mm ⁇ 27 mm, the thickness was 0.45 mm or less, and the capacity was 30 mAh.
  • the average orientation angle of the primary particles in the positive electrode active material plate 22 was 16°.
  • the average orientation angle was measured as follows. First, the above-mentioned LiCoO 2 sintered body plate was polished by a cross section polisher (CP) (IB-15000CP manufactured by JEOL Ltd.) to obtain a cross section (that is, perpendicular to the main surface of the LiCoO 2 sintered body plate). The cross section was subjected to EBSD measurement in a field of view (125 ⁇ m ⁇ 125 ⁇ m) of 1000 times to obtain an EBSD image.
  • CP cross section polisher
  • This EBSD measurement was performed using a Schottky field emission scanning electron microscope (JSM-7800F, manufactured by JEOL Ltd.). Then, for all the particles specified in the obtained EBSD image, the angle formed by the (003) plane of the primary particles and the main surface of the LiCoO 2 sintered body plate (that is, the inclination of the crystal orientation from (003)) was determined as the tilt angle, and the average value of these angles was defined as the average orientation angle of the primary particles.
  • JSM-7800F Schottky field emission scanning electron microscope
  • the plate thickness of the LiCoO 2 sintered body plate was 90 ⁇ m as described above.
  • the plate thickness is measured by polishing a LiCoO 2 sintered plate with a cross section polisher (CP) (manufactured by JEOL Ltd., IB-15000CP), and observing the obtained cross section by SEM (JSM6390LA, JEOL Ltd.). did.
  • the thickness of the LiCoO 2 green sheet after the above-mentioned drying was also measured in the same manner.
  • the porosity of the LiCoO 2 sintered body plate was 30%.
  • the porosity was measured as follows.
  • the LiCoO 2 sintered body plate was polished by a cross section polisher (CP) (manufactured by JEOL Ltd., IB-15000CP), and the obtained cross section was observed with an SEM under a field of view of 1000 times (125 ⁇ m ⁇ 125 ⁇ m). JSM6390LA).
  • the obtained SEM image was subjected to image analysis, the area of all the pores was divided by the area of the LiCoO 2 sintered body plate, and the obtained value was multiplied by 100 to calculate the porosity (%).
  • the average pore diameter of the LiCoO 2 sintered body plate was 0.8 ⁇ m.
  • the average pore diameter was measured by a mercury porosimetry using a mercury porosimeter (manufactured by Shimadzu Corporation, Autopore IV9510).
  • the lithium secondary battery 1 when the lithium secondary battery 1 is mounted on a smart card, the lithium secondary battery 1 is sandwiched between card base materials and cold laminated to press at room temperature, or the lithium secondary battery 1 is used as a card. Hot laminating is performed in which the substrate is sandwiched and heated and pressed.
  • the covering region 67 is compressed in the vertical direction, and the first sheet portion 65 and the first sheet portion 65 are compressed in the covering region 67. A part of the electrolytic solution 5 existing between the second sheet portion 66 and the second sheet portion 66 is extruded toward the periphery of the covering region 67.
  • the electrolytic solution 5 extruded from the covering region 67 flows between the first sheet portion 65 and the second sheet portion 66 which are in contact with or close to each other in the second region 682 in a non-bonded state, and as shown in FIG.
  • the first sheet portion 65 and the second sheet portion 66 are vertically separated from each other. Then, the electrolytic solution 5 is held in the space formed between the first sheet portion 65 and the second sheet portion 66 in the second region 682.
  • the electrolytic solution 5 penetrates between the first sheet portion 65 and the second sheet portion 66 joined in the first region 681 to separate the first sheet portion 65 and the second sheet portion 66 from each other. This can be prevented or suppressed. As a result, it is possible to prevent or suppress deterioration of the sealing performance of the outer package 6 and leakage of the electrolytic solution 5 from between the first sheet portion 65 and the second sheet portion 66.
  • the pressure applied to the lithium secondary battery 1 is removed, most of the electrolytic solution 5 that has diffused into the second region 682 returns to the coating region 67 due to a capillary phenomenon or the like. The same applies to the lithium secondary battery 1 (see FIGS. 7 to 9) in which the outer peripheral region 68 is folded back along the folding line 693 described above.
  • the electrolytic solution 5 may infiltrate between the first sheet portion 65 and the second sheet portion 66 joined in the first region 681, and may cause the first sheet portion 65 and the second sheet portion 66 to be separated from each other. is there. Further, the electrolytic solution 5 may leak to the outside of the lithium secondary battery 1 from between the peeled first sheet portion 65 and the second sheet portion 66.
  • the width of the second region 682 is excessively large, the size of the entire lithium secondary battery 1 is limited to some extent, so that the areas of the positive electrode active material plate 22 and the negative electrode active material layer 32 are reduced, and the battery characteristics are reduced. It may decrease. Specifically, the rate characteristics and cycle characteristics of the lithium secondary battery 1 may deteriorate.
  • A1/B3 in the table is a value obtained by dividing the above-mentioned second area width A1 by the active material area width B3.
  • A1/B3 is the ratio of the second region width A1 to the active material region width B3.
  • Comparative Examples 1 to 3 Examples 1 to 6 and Comparative Example 4, A1/B3 is changed.
  • the width of the first region 681 is 2 mm.
  • the liquid leakage in the table indicates the presence or absence of leakage of the electrolytic solution 5 when the lithium secondary battery 1 is subjected to substantially the same processing as the above hot lamination.
  • the hot plate press heated to 135° C. vertically pressurizes the lithium secondary battery 1 at a processing pressure of 3 MPa to determine whether the electrolytic solution 5 leaks to the outside of the lithium secondary battery 1. was visually confirmed.
  • the rate characteristics in the table are the dissolution ratio (%) obtained by dividing the second capacity by the first capacity described later.
  • the first capacity is a capacity calculated by charging the lithium secondary battery 1 at 0.2C to 4.2V and then discharging at 0.2C to 3.0V.
  • the second capacity is a capacity calculated by charging the lithium secondary battery 1 at 0.2C to 4.2V and then discharging at 1.0C to 3.0V.
  • the cycle characteristics in the table indicate that the lithium secondary battery 1 is charged up to 4.2 V at 0.5 C and discharged up to 3.0 V at 0.5 C, repeated 300 times, and the capacity of the lithium secondary battery 1 after the repetition is repeated. Is a value (%) obtained by dividing by the capacity of the lithium secondary battery 1 before repetition.
  • A1/B3 is less than 0.0067. In Examples 1 to 6, A1/B3 is 0.02 to 1.0. In Comparative Example 4, A1/B3 is 1.2. In Comparative Examples 1 to 3, leakage of the electrolytic solution 5 occurred. On the other hand, in Examples 1 to 6 and Comparative Example 4, the electrolyte solution 5 did not leak. Further, in Comparative Examples 1 to 3 and Examples 1 to 6, the rate characteristics were 70% to 73% and the cycle characteristics were 90% to 94%. On the other hand, in Comparative Example 4, the rate characteristic was low at 55% and the cycle characteristic was low at 49%.
  • the lithium secondary battery 1 includes the positive electrode 2, the separator 4, the negative electrode 3, the electrolytic solution 5, the outer casing 6, and the two terminals 7.
  • the separator 4 is arranged on the positive electrode 2 in a predetermined stacking direction.
  • the negative electrode 3 is arranged on the side of the separator 4 opposite to the positive electrode 2 in the stacking direction.
  • the electrolytic solution 5 impregnates the positive electrode 2, the negative electrode 3, and the separator 4.
  • the outer package 6 has a two-layer sheet portion (that is, the first sheet portion 65 and the second sheet portion 66) that covers the positive electrode 2 and the negative electrode 3 from both sides in the stacking direction.
  • the outer package 6 is a rectangular sheet-shaped member that accommodates the positive electrode 2, the separator 4, the negative electrode 3, and the electrolytic solution 5 therein.
  • the two terminals 7 are connected to the positive electrode 2 and the negative electrode 3 inside the exterior body 6, respectively.
  • the two terminals 7 extend to the outside of the exterior body 6.
  • the outer package 6 includes a covering region 67 and an outer peripheral region 68.
  • the covering region 67 is a rectangular region that overlaps the positive electrode 2, the separator 4, and the negative electrode 3 in the stacking direction.
  • the outer peripheral area 68 is a rectangular frame-shaped area surrounding the periphery of the covered area 67.
  • the outer peripheral area 68 includes a first area 681 and a second area 682.
  • the first region 681 is a strip-shaped region that extends along a pair of sides (that is, a pair of long sides 691) other than the side where the two terminals 7 are arranged. In the first region 681, the two-layer sheet portions (that is, the first sheet portion 65 and the second sheet portion 66) are joined.
  • the second region 682 is a strip-shaped region extending along the covering region 67 between at least one first region 681 of the pair of first regions 681 and the covering region 67.
  • the two-layer sheet portions that is, the first sheet portion 65 and the second sheet portion 66
  • the electrolytic solution 5 of the lithium secondary battery 1 when the electrolytic solution 5 of the lithium secondary battery 1 is extruded from the covering region 67 to the outer peripheral region 68, the first sheet portion 65 and the second sheet portion 66 are separated from each other in the second region 682, The electrolytic solution 5 can be held in the space between the first sheet portion 65 and the second sheet portion 66. Therefore, peeling of the first region 681 (that is, peeling between the first sheet portion 65 and the second sheet portion 66 in the first region 681) by the electrolytic solution 5 extruded from the covering region 67 can be suppressed. In addition, leakage of the electrolytic solution 5 to the outside of the lithium secondary battery 1 can be suppressed.
  • the value obtained by dividing the second area width A1 which is the dividend by the active material area width B3 which is the divisor is preferably 0.02 or more and 1 or less.
  • the active material region width B3 is obtained by dividing the positive electrode active material width which is the width of the active material region of the positive electrode 2 and the negative electrode active material width which is the width of the active material region of the negative electrode 3 in the width direction perpendicular to the pair of long sides 691.
  • the second region width A1 is the width of the one second region 682 when the second region 682 exists only between the one first region 681 and the covering region 67 of the pair of first regions 681. If there is a pair of second regions 682 between both the pair of first regions 681 and the covering region 67, the total width of the pair of second regions 682 is present. As a result, as shown in Examples 1 to 6 in Table 1, leakage of the electrolytic solution 5 from the lithium secondary battery 1 can be prevented and the battery characteristics (that is, rate characteristics and cycle characteristics) deteriorate. Can be prevented or suppressed.
  • the at least one first region 681 be folded back in the width direction at a folding line 693 extending parallel to the pair of long sides 691.
  • the size (so-called footprint) of the lithium secondary battery 1 in plan view can be reduced.
  • the target device in which the lithium secondary battery 1 is mounted can be downsized. Alternatively, it is possible to reduce the mounting space of the lithium secondary battery 1 in the target device.
  • the folding line 693 is located at the center of the at least one first region 681 in the width direction or on the opposite side of the second region 682 with respect to the center of the at least one first region 681 in the width direction. (See Figures 7 and 8). Accordingly, since the folded-back portion 695 does not vertically overlap the second region 682, the expansion of the second region 682 is caused by the expansion of the second region 682 when the electrolytic solution 5 extruded from the covering region 67 flows into the second region 682. Can be prevented. Therefore, the second region 682 is appropriately expanded, and the electrolytic solution 5 can be appropriately retained in the second region 682.
  • the folding line 693 is located between the center of the at least one first region 681 in the width direction and the second region 682 (see FIG. 9).
  • the folded-back portion 695 is folded back to a position on the inner side in the width direction that overlaps the second region 682 in the vertical direction.
  • the size of the lithium secondary battery 1 in plan view can be further reduced.
  • the positive electrode 2 includes the conductive sheet-shaped current collector (that is, the positive electrode current collector 21 ), and the active material plate (that is, the positive electrode current collector 21) that is the plate-shaped ceramic sintered body containing the lithium composite oxide (that is, The positive electrode active material plate 22) is preferably provided.
  • the battery characteristics of the lithium secondary battery 1 can be further improved.
  • the positive electrode active material plate 22 of the positive electrode 2 has a structure in which a plurality of primary particles having a layered rock salt structure are bonded.
  • the average tilt angle of the plurality of primary particles is preferably larger than 0° and 30° or less.
  • the average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the positive electrode active material plate 22.
  • the positive electrode active material plate 22 in contact with the conductive bonding layer 23 the main surface to which internal stress generated when the crystal lattice expands or contracts is not easily applied, the positive electrode active material plate 22 and the positive electrode It is possible to suppress a decrease in the bonding strength with the current collector 21. As a result, it is possible to improve the voltage stability during charging and discharging of the lithium secondary battery 1.
  • the lithium secondary battery 1 is particularly suitable as a power supply source in a thin and relatively deformable device, that is, a sheet-shaped device or a flexible device (for example, a smart card).
  • the lithium secondary battery 1 can suppress the leakage of the electrolytic solution 5, it is a target device that is subjected to the step of extruding the electrolytic solution 5 from the covering region 67 during manufacturing, that is, manufacturing. It is particularly suitable when it is used as a power supply source in a target device to which a step of applying pressure while heating is performed.
  • the second region width A1/active material region width B3 may be less than 0.02 as long as it is greater than 0.
  • the second area width A1/active material area width B3 may be larger than one. In any case, leakage of the electrolytic solution 5 to the outside of the lithium secondary battery 1 can be suppressed.
  • the folding line 693 is located on the first region 681, but the folding line 693 may be arranged on the second region 682.
  • a part of the folded-back portion 695 (that is, the end portion on the inner side in the width direction) may overlap the covering region 67 in the vertical direction.
  • the folded-back portion 695 is folded back by about 180° at the folded-back line 693, but the folded-back angle may be less than 180°.
  • the folding-back angle is an angle formed by the folding-back portion 695 before folding and the folding-back portion 695 after folding in the cross-sectional views as shown in FIGS. 7 to 9.
  • the folding angle is preferably 90° or more and 180° or less.
  • the folding part 695 is folded only once at the folding line 693, but the number of folding may be plural.
  • a portion on the outer side in the width direction of the first region 681 may be folded back multiple times inward in the width direction to form a folded portion 695 having a spiral cross section.
  • the second region 682 where the first sheet portion 65 and the second sheet portion 66 of the exterior body 6 are in contact with or close to each other in the non-bonded state is adjacent to the short side where the two terminals 7 are provided in the exterior body 6. However, it may be provided along a side other than the long side 691 (that is, another short side parallel to the short side where the two terminals 7 are provided).
  • the two terminals 7 do not necessarily have to extend from one side of the exterior body 6 to the outside of the exterior body 6, and may extend from the pair of parallel sides to the exterior of the exterior body 6, respectively.
  • the structure of the positive electrode active material plate 22 of the positive electrode 2 may be variously modified.
  • the average tilt angle of the plurality of primary particles having a layered rock salt structure may be larger than 30° or may be 0°.
  • the structure of the plurality of primary particles may be a structure other than the layered rock salt structure.
  • the positive electrode 2 may be a coated electrode in which a positive electrode active material layer containing a binder containing a resin as a main component and a positive electrode active material is coated on the positive electrode current collector 21.
  • the lithium secondary battery 1 is a flexible device other than a smart card (for example, a card type device) or a sheet-like device (for example, a wearable device provided on clothes or the like, or a body sticking type device). It may be used as a power supply source. Further, the lithium secondary battery 1 may be used as a power supply source for various objects (for example, IoT module) other than the above-mentioned devices.
  • the lithium secondary battery of the present invention can be used in various fields where the lithium secondary battery is used, for example, as a power supply source in a smart card having an arithmetic processing function.

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Abstract

An external body (6) of a lithium secondary battery (1) includes a coated region (67) and an outer peripheral region (68). The coated region (67) is a rectangular region in which a positive electrode (2), a separator (4), and a negative electrode (3) overlap in an overlapping direction. The outer peripheral region (68) is a rectangular frame-like region that surrounds the coated region (67). First regions (681) of the outer peripheral region (68) are belt-like regions that extend along a pair of long sides (691). In the first regions (681), a first sheet portion (65) and a second sheet portion (66) are bonded. A second region (682) is a belt-like region that extends along the coated region (67) between at least one of the pair of the first regions (681) and the coated region (67). In the second region (682), the first sheet portion (65) and the second sheet portion (66) contact each other or are in close proximity to each other without being bonded. Thus, leakage of an electrolyte (5) outside the lithium secondary battery (1) can be suppressed.

Description

リチウム二次電池Lithium secondary battery
　本発明は、薄型のリチウム二次電池に関する。 The present invention relates to a thin lithium secondary battery.
　従来、薄型電池は、様々な機器等に搭載されて電力供給源として利用されている。例えば、特開２０１６－１３９４９４号公報（文献１）では、２枚のフィルムを重ね合わせたラミネート部材と、当該２枚のフィルムの間に収納された電池セルとを有するラミネート型電池が開示されている。当該ラミネート型電池では、ラミネート型電池が搭載される機器において電池収納スペースを小型化することを目的として、ラミネート部材の周縁部が折り畳まれている。 Conventionally, thin batteries have been installed in various devices and used as a power supply source. For example, Japanese Unexamined Patent Application Publication No. 2016-139494 (Reference 1) discloses a laminate type battery including a laminate member in which two films are stacked and a battery cell housed between the two films. There is. In the laminate type battery, the peripheral edge portion of the laminate member is folded in order to reduce the battery storage space in the device in which the laminate type battery is mounted.
　また、特開２０１５－１５３５１３号公報（文献２）のラミネート外装電池においても同様に、スペース効率の向上を目的として、ラミネート外装体の両側部が９０°折り曲げられている。特開２００９－３２６１２号公報（文献３）のラミネート外装電池では、ラミネートフィルムの局所的な変形を抑制して絶縁不良を抑制することを目的として、ラミネートフィルムの両側部が９０°折り曲げられている。 Similarly, in the laminated outer battery disclosed in JP-A-2015-153513 (Reference 2), both sides of the laminated outer body are bent by 90° for the purpose of improving space efficiency. In the laminated outer battery of JP 2009-32612 A (Reference 3), both sides of the laminated film are bent by 90° for the purpose of suppressing local deformation of the laminated film and suppressing insulation failure. ..
　近年、スマートカードの電力供給源として、薄型のリチウム二次電池（リチウムイオン二次電池とも呼ぶ。）の利用が検討されている。当該スマートカードの製造方法として、リチウム二次電池をカード基材で挟み込んで常温にて加圧するコールドラミネート、および、リチウム二次電池をカード基材で挟み込んで加熱および加圧するホットラミネート等が知られている。 In recent years, the use of thin lithium secondary batteries (also called lithium-ion secondary batteries) has been considered as a power supply source for smart cards. Known methods for manufacturing the smart card include a cold laminate in which a lithium secondary battery is sandwiched between card base materials and pressed at room temperature, and a hot laminate in which a lithium secondary battery is sandwiched between card base materials and heated and pressed. ing.
　一方、特開２００５－７４９３６号公報（文献４）は、薄型電池ではなくＩＣチップが搭載されたＩＣカードの製造方法に関するものである。ＩＣカードの製造においても、ＩＣチップを間に挟んだ２枚の基体シートで挟み込んで加熱および加圧する工程が行われる。 On the other hand, Japanese Unexamined Patent Publication No. 2005-74936 (Reference 4) relates to a method of manufacturing an IC card having an IC chip mounted instead of a thin battery. Also in the manufacture of an IC card, a step of sandwiching an IC chip between two base sheet and heating and pressing is performed.
　ところで、リチウム二次電池が搭載されたスマートカード等を製造する場合、上述のホットラミネート等が行われる際にリチウム二次電池が圧迫され、電池内部に充填されている電解液が、電池外部へと漏出するおそれがある。 By the way, when manufacturing a smart card or the like equipped with a lithium secondary battery, the lithium secondary battery is pressed when the above-mentioned hot lamination is performed, and the electrolytic solution filled inside the battery is discharged to the outside of the battery. There is a risk of leakage.
　本発明は、薄型のリチウム二次電池に向けられており、リチウム二次電池の外部への電解液の漏出を抑制することを目的としている。 The present invention is directed to a thin lithium secondary battery, and an object thereof is to suppress leakage of an electrolytic solution to the outside of the lithium secondary battery.
　本発明の好ましい一の形態に係るリチウム二次電池は、正極と、所定の重ね合わせ方向において前記正極上に配置されるセパレータと、前記重ね合わせ方向において前記セパレータの前記正極とは反対側に配置される負極と、前記正極、前記負極および前記セパレータに含浸する電解液と、前記重ね合わせ方向の両側から前記正極および前記負極を被覆する２層のシート部を有するとともに、前記正極、前記セパレータ、前記負極および前記電解液を内部に収容する矩形シート状の外装体と、前記外装体の内部にて前記正極および前記負極にそれぞれ接続されるとともに前記外装体の外部へと延びる２つの端子と、を備える。前記外装体は、前記正極、前記セパレータおよび前記負極と前記重ね合わせ方向に重なる矩形状の被覆領域と、前記被覆領域の周囲を囲む矩形枠状の外周領域と、を備える。前記外周領域は、前記２つの端子が配置される辺以外の一対の辺に沿ってそれぞれ延びる帯状領域であって前記２層のシート部が接合される一対の第１領域と、前記一対の第１領域のうち少なくとも一方の第１領域と前記被覆領域との間にて前記被覆領域に沿って延びる帯状領域であって前記２層のシート部が非接合状態にて接触または近接する第２領域と、を備える。これにより、リチウム二次電池の外部への電解液の漏出を抑制することができる。 A lithium secondary battery according to a preferred embodiment of the present invention is a positive electrode, a separator arranged on the positive electrode in a predetermined stacking direction, and a separator opposite to the positive electrode of the separator in the stacking direction. With the negative electrode, the positive electrode, the electrolytic solution impregnating the negative electrode and the separator, and having a two-layer sheet portion that covers the positive electrode and the negative electrode from both sides in the stacking direction, the positive electrode, the separator, A rectangular sheet-shaped exterior body that accommodates the negative electrode and the electrolytic solution therein, and two terminals that are connected to the positive electrode and the negative electrode inside the exterior body and extend to the outside of the exterior body, respectively. Equipped with. The exterior body includes a rectangular coating region that overlaps the positive electrode, the separator, and the negative electrode in the stacking direction, and a rectangular frame-shaped outer peripheral region that surrounds the periphery of the coating region. The outer peripheral region is a strip-shaped region that extends along a pair of sides other than the side on which the two terminals are arranged, and is a pair of first regions to which the two-layer sheet portions are joined and a pair of first regions. A second region, which is a strip-shaped region extending along at least one of the first region and the covering region, and in which the two-layer sheet portions are in contact with or close to each other in a non-bonded state. And This makes it possible to suppress the leakage of the electrolytic solution to the outside of the lithium secondary battery.
　好ましくは、前記一対の辺に垂直な幅方向における前記正極の活物質領域の幅である正極活物質幅と前記負極の活物質領域の幅である負極活物質幅とが異なる場合は、前記正極活物質幅および前記負極活物質幅のうち小さい方を除数とし、前記正極活物質幅と前記負極活物質幅とが同じである場合は前記正極活物質幅および前記負極活物質幅のうちいずれか一方を除数として、前記一対の第１領域のうち一方の第１領域と前記被覆領域との間にのみ前記第２領域が存在する場合は前記第２領域の幅を被除数とし、前記一対の第１領域の双方と前記被覆領域との間に一対の前記第２領域が存在する場合は前記一対の第２領域の合計幅を被除数として、前記被除数を前記除数により除算した値は、０．０２以上かつ１以下である。 Preferably, when the positive electrode active material width which is the width of the positive electrode active material region in the width direction perpendicular to the pair of sides and the negative electrode active material width which is the width of the negative electrode active material region are different, the positive electrode The smaller one of the active material width and the negative electrode active material width is taken as a divisor, and when the positive electrode active material width and the negative electrode active material width are the same, one of the positive electrode active material width and the negative electrode active material width When one is a divisor, and the second region is present only between one of the pair of first regions and the covering region, the width of the second region is the dividend, and the pair of first regions When a pair of the second regions is present between both of the one region and the covering region, the total width of the pair of the second regions is taken as the dividend, and the value obtained by dividing the dividend by the divisor is 0.02. It is above 1 and below 1.
　好ましくは、前記少なくとも一方の第１領域は、前記一対の辺に平行に延びる折り返し線にて幅方向に折り返されている。 Preferably, the at least one first region is folded back in the width direction by a folding line extending parallel to the pair of sides.
　好ましくは、前記折り返し線は、前記少なくとも一方の第１領域の幅方向の中央、または、前記少なくとも一方の第１領域の幅方向の中央に対して前記第２領域の反対側に位置する。 Preferably, the folding line is located on the opposite side of the second region with respect to the center of the at least one first region in the width direction or the center of the at least one first region in the width direction.
　好ましくは、前記折り返し線は、前記少なくとも一方の第１領域の幅方向の中央と前記第２領域との間に位置する。 Preferably, the folding line is located between the widthwise center of the at least one first region and the second region.
　好ましくは、前記正極は、導電性を有するシート状の集電体と、リチウム複合酸化物を含む板状セラミック焼結体である活物質板と、を備える。 Preferably, the positive electrode includes a sheet-shaped current collector having conductivity and an active material plate which is a plate-shaped ceramic sintered body containing a lithium composite oxide.
　好ましくは、前記活物質板は、層状岩塩構造を有する複数の一次粒子が結合した構造を有している。前記複数の一次粒子の平均傾斜角は、０°よりも大きく、かつ、３０°以下である。前記平均傾斜角は、前記複数の一次粒子の（００３）面と前記活物質板の主面とが成す角度の平均値である。 Preferably, the active material plate has a structure in which a plurality of primary particles having a layered rock salt structure are bonded. The average inclination angle of the plurality of primary particles is greater than 0° and 30° or less. The average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the active material plate.
　好ましくは、前記リチウム二次電池は、シート状デバイス、または、可撓性を有するデバイスにおける電力供給源として利用される。 Preferably, the lithium secondary battery is used as a power supply source in a sheet-shaped device or a flexible device.
　好ましくは、前記リチウム二次電池は、前記可撓性を有するデバイスであるスマートカードにおける電力供給源として利用される。 Preferably, the lithium secondary battery is used as a power supply source in a smart card, which is the flexible device.
　好ましくは、前記リチウム二次電池は、製造の際に加熱しつつ加圧する工程が施される対象デバイスにおける電力供給源として利用される。 Preferably, the lithium secondary battery is used as a power supply source in a target device that is subjected to a step of heating and pressurizing during manufacturing.
　上述の目的および他の目的、特徴、態様および利点は、添付した図面を参照して以下に行うこの発明の詳細な説明により明らかにされる。 The above objects and other objects, features, aspects and advantages will be made clear by the detailed description of the present invention given below with reference to the accompanying drawings.
一の実施の形態に係るリチウム二次電池の断面図である。FIG. 3 is a cross-sectional view of a lithium secondary battery according to one embodiment. リチウム二次電池の平面図である。It is a top view of a lithium secondary battery. 他のリチウム二次電池の断面図である。It is sectional drawing of another lithium secondary battery. リチウム二次電池の断面図である。It is sectional drawing of a lithium secondary battery. リチウム二次電池の断面図である。It is sectional drawing of a lithium secondary battery. リチウム二次電池の平面図である。It is a top view of a lithium secondary battery. リチウム二次電池の断面図である。It is sectional drawing of a lithium secondary battery. リチウム二次電池の断面図である。It is sectional drawing of a lithium secondary battery. リチウム二次電池の断面図である。It is sectional drawing of a lithium secondary battery. リチウム二次電池の製造の流れを示す図である。It is a figure which shows the flow of manufacture of a lithium secondary battery. リチウム二次電池の製造の流れを示す図である。It is a figure which shows the flow of manufacture of a lithium secondary battery. リチウム二次電池の断面図である。It is sectional drawing of a lithium secondary battery.
　図１は、本発明の一の実施の形態に係るリチウム二次電池１の構成を示す断面図である。図２は、リチウム二次電池１の平面図である。図１では、図の理解を容易にするために、リチウム二次電池１およびその構成を、実際よりも厚く描いている。なお、図１では、断面よりも手前側および奥側の一部の構造を併せて図示する。図３においても同様である。 FIG. 1 is a sectional view showing the configuration of a lithium secondary battery 1 according to an embodiment of the present invention. FIG. 2 is a plan view of the lithium secondary battery 1. In FIG. 1, in order to facilitate understanding of the drawing, the lithium secondary battery 1 and its configuration are drawn thicker than they actually are. In addition, in FIG. 1, a part of the structure on the front side and the back side of the cross section is also illustrated. The same applies to FIG.
　リチウム二次電池１は、小型かつ薄型の電池である。リチウム二次電池１の平面視における形状は、例えば略矩形状である。例えば、リチウム二次電池１の平面視における縦方向の長さは１０ｍｍ～４６ｍｍであり、横方向の長さは１０ｍｍ～４６ｍｍである。リチウム二次電池１の厚さ（すなわち、図１中の上下方向の厚さ）は、例えば０．３０ｍｍ～０．４５ｍｍであり、好ましくは０．４０ｍｍ～０．４５ｍｍである。リチウム二次電池１は、シート状または可撓性を有する薄板状の部材である。シート状の部材とは、比較的小さい力によって容易に変形する薄い部材であり、フィルム状の部材とも呼ばれる。以下の説明においても同様である。 The lithium secondary battery 1 is a small and thin battery. The shape of the lithium secondary battery 1 in a plan view is, for example, a substantially rectangular shape. For example, the length of the lithium secondary battery 1 in the vertical direction in plan view is 10 mm to 46 mm, and the length in the horizontal direction is 10 mm to 46 mm. The thickness of the lithium secondary battery 1 (that is, the thickness in the vertical direction in FIG. 1) is, for example, 0.30 mm to 0.45 mm, preferably 0.40 mm to 0.45 mm. The lithium secondary battery 1 is a sheet-shaped or flexible thin plate-shaped member. The sheet-shaped member is a thin member that is easily deformed by a relatively small force, and is also called a film-shaped member. The same applies to the following description.
　リチウム二次電池１は、例えば、シート状デバイス、または、可撓性を有するデバイスに搭載されて電力供給源として利用される。シート状デバイスとは、比較的小さい力によって容易に変形する薄いデバイスであり、フィルム状デバイスとも呼ばれる。本実施の形態では、リチウム二次電池１は、例えば、演算処理機能を有するスマートカードに内蔵され、当該スマートカードにおける電力供給源として利用される。スマートカードは、カード型の可撓性を有するデバイスである。スマートカードは、例えば、無線通信ＩＣ、指紋解析用ＡＳＩＣおよび指紋センサを備えた指紋認証・無線通信機能付きカード等として用いられる。以下の説明では、スマートカード等のように、リチウム二次電池１が電力供給源として利用される対象となるデバイスを「対象デバイス」とも呼ぶ。 The lithium secondary battery 1 is mounted on, for example, a sheet-shaped device or a flexible device and used as a power supply source. The sheet-like device is a thin device that is easily deformed by a relatively small force, and is also called a film-like device. In the present embodiment, the lithium secondary battery 1 is, for example, built in a smart card having an arithmetic processing function and used as a power supply source in the smart card. A smart card is a card-type flexible device. The smart card is used as, for example, a card with a fingerprint authentication/wireless communication function including a wireless communication IC, a fingerprint analysis ASIC, and a fingerprint sensor. In the following description, a device for which the lithium secondary battery 1 is used as a power supply source, such as a smart card, is also referred to as a “target device”.
　スマートカードへのリチウム二次電池１の搭載は、例えば、常温にて加圧を行うコールドラミネート、または、加熱しつつ加圧を行うホットラミネートにより行われる。ホットラミネートにおける加工温度は、例えば１１０℃～２６０℃である。当該加工温度の上限は、好ましくは２４０℃未満であり、より好ましくは２２０℃未満であり、さらに好ましくは２００℃未満であり、最も好ましくは１５０℃以下である。また、ホットラミネートにおける加工圧力は、例えば０．１ＭＰａ（メガパスカル）～６ＭＰａであり、加工時間（すなわち、加熱・加圧時間）は、例えば１０分～２０分である。 The mounting of the lithium secondary battery 1 on the smart card is performed by, for example, cold lamination in which pressure is applied at room temperature or hot lamination in which pressure is applied while heating. The processing temperature in hot lamination is, for example, 110°C to 260°C. The upper limit of the processing temperature is preferably lower than 240°C, more preferably lower than 220°C, further preferably lower than 200°C, and most preferably 150°C or lower. The processing pressure in hot lamination is, for example, 0.1 MPa (megapascal) to 6 MPa, and the processing time (that is, heating/pressurizing time) is, for example, 10 to 20 minutes.
　リチウム二次電池１は、正極２と、負極３と、セパレータ４と、電解液５と、外装体６と、２つの端子７とを備える。正極２、セパレータ４および負極３は、所定の重ね合わせ方向に重ね合わせられている。図１に示す例では、正極２、セパレータ４および負極３は、図中の上下方向に積層されている。以下の説明では、図１中の上側および下側を、単に「上側」および「下側」と呼ぶ。また、図１中の上下方向を、単に「上下方向」と呼び、「重ね合わせ方向」とも呼ぶ。図１中の上下方向は、リチウム二次電池１がスマートカード等の対象デバイスに搭載される際の実際の上下方向と一致する必要はない。 The lithium secondary battery 1 includes a positive electrode 2, a negative electrode 3, a separator 4, an electrolytic solution 5, an outer casing 6, and two terminals 7. The positive electrode 2, the separator 4, and the negative electrode 3 are stacked in a predetermined stacking direction. In the example shown in FIG. 1, the positive electrode 2, the separator 4, and the negative electrode 3 are stacked in the vertical direction in the figure. In the following description, the upper side and the lower side in FIG. 1 are simply referred to as “upper side” and “lower side”. Further, the up-down direction in FIG. 1 is simply referred to as “up-down direction” and also referred to as “overlapping direction”. The vertical direction in FIG. 1 does not have to match the actual vertical direction when the lithium secondary battery 1 is mounted on a target device such as a smart card.
　図１に示す例では、セパレータ４は、上下方向（すなわち、重ね合わせ方向）において正極２の上面上に配置される。負極３は、上下方向においてセパレータ４の上面上に配置される。換言すれば、負極３は、上下方向においてセパレータ４の正極２とは反対側に配置される。正極２、セパレータ４および負極３はそれぞれ、平面視において例えば略矩形状である。正極２、セパレータ４および負極３は、平面視においておよそ同形状（すなわち、およそ同じ形、かつ、およそ同じ大きさ）である。 In the example shown in FIG. 1, the separator 4 is arranged on the upper surface of the positive electrode 2 in the vertical direction (that is, the stacking direction). The negative electrode 3 is arranged on the upper surface of the separator 4 in the vertical direction. In other words, the negative electrode 3 is arranged on the side of the separator 4 opposite to the positive electrode 2 in the vertical direction. Each of the positive electrode 2, the separator 4, and the negative electrode 3 has, for example, a substantially rectangular shape in a plan view. The positive electrode 2, the separator 4, and the negative electrode 3 have approximately the same shape in plan view (that is, approximately the same shape and approximately the same size).
　外装体６は、シート状かつ袋状の部材である。外装体６は、平面視において略矩形である。外装体６は、上下方向に重なる２層のシート部６５，６６を備える。以下の説明では、正極２の下側に位置するシート部６５を「第１シート部６５」と呼び、負極３の上側に位置するシート部６６を「第２シート部６６」と呼ぶ。第１シート部６５の外周縁と第２シート部６６の外周縁とは、例えば熱融着（いわゆる、ヒートシール）により接合されている。外装体６の第１シート部６５および第２シート部６６はそれぞれ、例えば、アルミニウム（Ａｌ）等の金属により形成された金属箔６１と、絶縁性の樹脂層６２とが積層されたラミネートフィルムにより形成される。第１シート部６５および第２シート部６６では、樹脂層６２は、金属箔６１の内側に位置する。 The exterior body 6 is a sheet-shaped and bag-shaped member. The exterior body 6 is substantially rectangular in plan view. The exterior body 6 includes two layers of sheet portions 65 and 66 that are vertically overlapped with each other. In the following description, the sheet portion 65 located below the positive electrode 2 is referred to as “first sheet portion 65”, and the sheet portion 66 located above the negative electrode 3 is referred to as “second sheet portion 66”. The outer peripheral edge of the first sheet portion 65 and the outer peripheral edge of the second sheet portion 66 are joined by, for example, heat fusion (so-called heat sealing). The first sheet portion 65 and the second sheet portion 66 of the outer package 6 are each made of, for example, a laminated film in which a metal foil 61 formed of a metal such as aluminum (Al) and an insulating resin layer 62 are laminated. It is formed. In the first sheet portion 65 and the second sheet portion 66, the resin layer 62 is located inside the metal foil 61.
　外装体６は、上下方向の両側から正極２および負極３を被覆する。外装体６は、正極２、セパレータ４、負極３および電解液５を内部に収容する。電解液５は、正極２、セパレータ４および負極３の周囲に連続して存在する。換言すれば、電解液５は、正極２および負極３の間に介在する。電解液５は、正極２、セパレータ４および負極３に含浸している。２つの端子７は、外装体６の内部から外部へと延びる。外装体６の内部において、一方の端子７は正極２に電気的に接続されており、他方の端子７は負極３に電気的に接続されている。 The exterior body 6 covers the positive electrode 2 and the negative electrode 3 from both sides in the vertical direction. The outer package 6 houses the positive electrode 2, the separator 4, the negative electrode 3, and the electrolytic solution 5 therein. The electrolytic solution 5 continuously exists around the positive electrode 2, the separator 4, and the negative electrode 3. In other words, the electrolytic solution 5 is interposed between the positive electrode 2 and the negative electrode 3. The electrolytic solution 5 impregnates the positive electrode 2, the separator 4, and the negative electrode 3. The two terminals 7 extend from the inside of the exterior body 6 to the outside. Inside the outer package 6, one terminal 7 is electrically connected to the positive electrode 2, and the other terminal 7 is electrically connected to the negative electrode 3.
　正極２は、正極集電体２１と、正極活物質板２２と、導電性接合層２３とを備える。正極集電体２１は、導電性を有するシート状の部材である。正極集電体２１の下面は、正極接合層６３を介して外装体６の樹脂層６２に接合されている。正極接合層６３は、例えば、酸変性ポリオレフィン系樹脂とエポキシ系樹脂との混合樹脂により形成される。正極接合層６３は、他の様々な材料により形成されてもよい。正極接合層６３の厚さは、例えば０．５μｍ～１０μｍである。 The positive electrode 2 includes a positive electrode current collector 21, a positive electrode active material plate 22, and a conductive bonding layer 23. The positive electrode current collector 21 is a conductive sheet-shaped member. The lower surface of the positive electrode current collector 21 is bonded to the resin layer 62 of the exterior body 6 via the positive electrode bonding layer 63. The positive electrode bonding layer 63 is formed of, for example, a mixed resin of acid-modified polyolefin-based resin and epoxy-based resin. The positive electrode bonding layer 63 may be formed of various other materials. The thickness of the positive electrode bonding layer 63 is, for example, 0.5 μm to 10 μm.
　正極集電体２１は、例えば、アルミニウム等の金属により形成される金属箔と、当該金属箔の上面上に積層された導電性カーボン層とを備える。換言すれば、正極集電体２１の正極活物質板２２に対向する主面は、導電性カーボン層により被覆されている。上述の金属箔は、アルミニウム以外の様々な金属（例えば、銅、ニッケル、銀、金、クロム、鉄、スズ、鉛、タングステン、モリブデン、チタン、亜鉛、または、これらを含む合金等）により形成されてもよい。また、正極集電体２１から上記導電性カーボン層は省略されてもよい。 The positive electrode current collector 21 includes, for example, a metal foil formed of a metal such as aluminum and a conductive carbon layer laminated on the upper surface of the metal foil. In other words, the main surface of the positive electrode current collector 21 facing the positive electrode active material plate 22 is covered with the conductive carbon layer. The metal foil described above is formed of various metals other than aluminum (for example, copper, nickel, silver, gold, chromium, iron, tin, lead, tungsten, molybdenum, titanium, zinc, or alloys containing these). May be. Further, the conductive carbon layer may be omitted from the positive electrode current collector 21.
　正極活物質板２２（すなわち、正極２の活物質板）は、リチウム複合酸化物を含む比較的薄い板状セラミック焼結体である。正極活物質板２２は、導電性接合層２３を介して正極集電体２１の上面上に接合される。正極活物質板２２は、上下方向においてセパレータ４と対向する。正極活物質板２２の上面は、セパレータ４の下面と接触する。正極活物質板２２は、実質的に樹脂を含んでいない。したがって、正極２のセパレータ４に対向する主面（すなわち、図１中の上面）は、実質的に樹脂を含んでいない。 The positive electrode active material plate 22 (that is, the active material plate of the positive electrode 2) is a relatively thin plate-shaped ceramic sintered body containing a lithium composite oxide. The positive electrode active material plate 22 is bonded onto the upper surface of the positive electrode current collector 21 via the conductive bonding layer 23. The positive electrode active material plate 22 faces the separator 4 in the vertical direction. The upper surface of the positive electrode active material plate 22 contacts the lower surface of the separator 4. The positive electrode active material plate 22 contains substantially no resin. Therefore, the main surface of the positive electrode 2 facing the separator 4 (that is, the upper surface in FIG. 1) contains substantially no resin.
　正極活物質板２２は、複数の（すなわち、多数の）一次粒子が結合した構造を有している。当該一次粒子は、層状岩塩構造を有するリチウム複合酸化物で構成される。リチウム複合酸化物は、典型的には、一般式：ＬｉｐＭＯ２（式中、０．０５＜ｐ＜１．１０）で表される酸化物である。Ｍは少なくとも１種類の遷移金属であり、例えば、コバルト（Ｃｏ）、ニッケル（Ｎｉ）およびマンガン（Ｍｎ）から選択される１種以上を含む。層状岩塩構造とは、リチウム層とリチウム以外の遷移金属層とが酸素の層を挟んで交互に積層された結晶構造である。すなわち、層状岩塩構造は、酸化物イオンを介して遷移金属イオン層とリチウム単独層とが交互に積層した結晶構造（典型的には、α－ＮａＦｅＯ２型構造：立方晶岩塩型構造の［１１１］軸方向に遷移金属とリチウムとが規則配列した構造）である。 The positive electrode active material plate 22 has a structure in which a plurality of (that is, a large number of) primary particles are bonded. The primary particles are composed of a lithium composite oxide having a layered rock salt structure. The lithium composite oxide is typically an oxide represented by the general formula: Li p MO 2 (wherein 0.05<p<1.10). M is at least one kind of transition metal, and includes, for example, one or more kinds selected from cobalt (Co), nickel (Ni) and manganese (Mn). The layered rock salt structure is a crystal structure in which lithium layers and transition metal layers other than lithium are alternately stacked with an oxygen layer in between. That is, the layered rock salt structure has a crystal structure in which transition metal ion layers and lithium single layers are alternately stacked via oxide ions (typically, α-NaFeO 2 type structure: cubic rock salt type structure [111 ] A structure in which a transition metal and lithium are regularly arranged in the axial direction).
　層状岩塩構造を有するリチウム複合酸化物の好ましい例としては、コバルト酸リチウム（ＬｉｐＣｏＯ２（式中、１≦ｐ≦１．１）、ニッケル酸リチウム（ＬｉＮｉＯ２）、マンガン酸リチウム（Ｌｉ２ＭｎＯ３）、ニッケルマンガン酸リチウム（Ｌｉｐ（Ｎｉ０．５，Ｍｎ０．５）Ｏ２）、一般式：Ｌｉｐ（Ｃｏｘ，Ｎｉｙ，Ｍｎｚ）Ｏ２（式中、０．９７≦ｐ≦１．０７，ｘ＋ｙ＋ｚ＝１）で表される固溶体、Ｌｉｐ（Ｃｏｘ，Ｎｉｙ，Ａｌｚ）Ｏ２（式中、０．９７≦ｐ≦１．０７、ｘ＋ｙ＋ｚ＝１、０＜ｘ≦０．２５、０．６≦ｙ≦０．９および０＜ｚ≦０．１）で表される固溶体、または、Ｌｉ２ＭｎＯ３とＬｉＭＯ２（式中、ＭはＣｏ、Ｎｉ等の遷移金属）との固溶体が挙げられる。特に好ましくは、リチウム複合酸化物はコバルト酸リチウムＬｉｐＣｏＯ２（式中、１≦ｐ≦１．１）であり、例えば、ＬｉＣｏＯ２（ＬＣＯ）である。 Preferred examples of the lithium composite oxide having a layered rock salt structure include lithium cobalt oxide (Li p CoO 2 (wherein 1≦p≦1.1), lithium nickel oxide (LiNiO 2 ), and lithium manganate (Li 2 MnO 3), lithium nickel manganese oxide (Li p (Ni 0.5, Mn 0.5) O 2), the general formula: Li p (Co x, Ni y, in Mn z) O 2 (wherein 0.97 ≦p≦1.07, x+y+z=1), a solid solution represented by Li p (Co x , Ni y , Al z )O 2 (wherein 0.97≦p≦1.07, x+y+z=1, 0< x≦0.25, 0.6≦y≦0.9 and 0<z≦0.1), or a solid solution represented by Li 2 MnO 3 and LiMO 2 (wherein M is Co, Ni, or the like). And a solid solution with a transition metal). Particularly preferably, the lithium composite oxide is lithium cobalt oxide Li p CoO 2 (wherein 1≦p≦1.1), for example, LiCoO 2 (LCO). ..
　なお、正極活物質板２２は、マグネシウム（Ｍｇ）、アルミニウム、ケイ素（Ｓｉ）、カルシウム（Ｃａ）、チタン（Ｔｉ）、バナジウム（Ｖ）、クロム（Ｃｒ）、鉄（Ｆｅ）、銅（Ｃｕ）、亜鉛（Ｚｎ）、ガリウム（Ｇａ）、ゲルマニウム（Ｇｅ）、ストロンチウム（Ｓｒ）、イットリウム（Ｙ）、ジルコニア（Ｚｒ）、ニオブ（Ｎｂ）、モリブデン（Ｍｏ）、銀（Ａｇ）、スズ（Ｓｎ）、アンチモン（Ｓｂ）、テルル（Ｔｅ）、バリウム（Ｂａ）、ビスマス（Ｂｉ）等の元素を１種類以上さらに含んでいてもよい。また、正極活物質板２２には、集電助剤として金（Ａｕ）等がスパッタされていてもよい。 The positive electrode active material plate 22 includes magnesium (Mg), aluminum, silicon (Si), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu). , Zinc (Zn), gallium (Ga), germanium (Ge), strontium (Sr), yttrium (Y), zirconia (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), tin (Sn). , Antimony (Sb), tellurium (Te), barium (Ba), bismuth (Bi), and the like may be further included in one or more kinds. In addition, the positive electrode active material plate 22 may be sputtered with gold (Au) or the like as a current collecting aid.
　正極活物質板２２において、上記複数の一次粒子の平均粒径である一次粒径は、例えば２０μｍ以下であり、好ましくは１５μｍ以下である。また、当該一次粒径は、例えば０．２μｍ以上であり、好ましくは０．４μｍ以上である。当該一次粒径は、正極活物質板２２の断面のＳＥＭ（走査型電子顕微鏡）画像を解析することにより測定することができる。具体的には、例えば、正極活物質板２２をクロスセクションポリッシャ（ＣＰ）で加工して研磨断面を露出させ、当該研磨断面を所定の倍率（例えば、１０００倍）および所定の視野（例えば、１２５μｍ×１２５μｍ）でＳＥＭにより観察する。このとき、視野内に２０個以上の一次粒子が存在するように視野を設定する。得られたＳＥＭ画像中の全ての一次粒子について外接円を描いたときの当該外接円の直径を求め、これらの平均値を一次粒径とする。 In the positive electrode active material plate 22, the average primary particle size of the plurality of primary particles is, for example, 20 μm or less, preferably 15 μm or less. The primary particle size is, for example, 0.2 μm or more, preferably 0.4 μm or more. The primary particle size can be measured by analyzing an SEM (scanning electron microscope) image of the cross section of the positive electrode active material plate 22. Specifically, for example, the positive electrode active material plate 22 is processed by a cross section polisher (CP) to expose a polished cross section, and the polished cross section is subjected to a predetermined magnification (for example, 1000 times) and a predetermined visual field (for example, 125 μm). ×125 μm) and observed by SEM. At this time, the visual field is set so that 20 or more primary particles are present in the visual field. The diameter of the circumscribed circle when the circumscribed circle is drawn for all the primary particles in the obtained SEM image is determined, and the average value of these is taken as the primary particle size.
　正極活物質板２２において、複数の一次粒子の平均傾斜角（すなわち、平均配向角度）は、０°よりも大きく、かつ、３０°以下であることが好ましい。また、当該平均傾斜角は、より好ましくは５°以上かつ２８°以下であり、さらに好ましくは１０°以上かつ２５°以下である。当該平均傾斜角は、複数の一次粒子の（００３）面と、正極活物質板２２の主面（例えば、正極活物質板２２の下面）とが成す角度の平均値である。 In the positive electrode active material plate 22, the average tilt angle (that is, the average orientation angle) of the plurality of primary particles is preferably larger than 0° and 30° or less. The average tilt angle is more preferably 5° or more and 28° or less, and further preferably 10° or more and 25° or less. The average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the positive electrode active material plate 22 (for example, the lower surface of the positive electrode active material plate 22).
　一次粒子の傾斜角（すなわち、一次粒子の（００３）面と正極活物質板２２の主面とが成す角度）は、正極活物質板２２の断面を電子線後方散乱回折法（ＥＢＳＤ）により解析することによって測定することができる。具体的には、例えば、正極活物質板２２をクロスセクションポリッシャで加工して研磨断面を露出させ、当該研磨断面を所定の倍率（例えば、１０００倍）および所定の視野（例えば、１２５μｍ×１２５μｍ）でＥＢＳＤにより解析する。得られたＥＢＳＤ像において、各一次粒子の傾斜角は色の濃淡で表され、色が濃いほど傾斜角が小さいことを示す。そして、ＥＢＳＤ像から求められた複数の一次粒子の傾斜角の平均値が、上述の平均傾斜角とされる。 The tilt angle of the primary particles (that is, the angle formed by the (003) plane of the primary particles and the main surface of the positive electrode active material plate 22) was analyzed by electron beam backscattering diffraction (EBSD) on the cross section of the positive electrode active material plate 22. It can be measured by Specifically, for example, the positive electrode active material plate 22 is processed by a cross section polisher to expose a polished cross section, and the polished cross section has a predetermined magnification (for example, 1000 times) and a predetermined visual field (for example, 125 μm×125 μm). Analyze by EBSD at. In the obtained EBSD image, the tilt angle of each primary particle is represented by the shade of color, and the darker the color, the smaller the tilt angle. Then, the average value of the inclination angles of the plurality of primary particles obtained from the EBSD image is set as the above-mentioned average inclination angle.
　正極活物質板２２を構成する一次粒子において、傾斜角が０°よりも大きくかつ３０°以下である一次粒子の占める割合は、好ましくは６０％以上であり、より好ましくは８０％以上であり、さらに好ましくは９０％以上である。当該割合の上限値は特に限定されず、１００％であってもよい。当該割合は、上述のＥＢＳＤ像において、傾斜角が０°よりも大きくかつ３０°以下である一次粒子の合計面積を求め、当該一次粒子の合計面積を全粒子面積で除算することにより求めることができる。 In the primary particles constituting the positive electrode active material plate 22, the proportion of the primary particles having a tilt angle of more than 0° and 30° or less is preferably 60% or more, more preferably 80% or more, More preferably, it is 90% or more. The upper limit of the ratio is not particularly limited and may be 100%. The ratio can be obtained by obtaining the total area of the primary particles having an inclination angle larger than 0° and 30° or less in the above EBSD image and dividing the total area of the primary particles by the total particle area. it can.
　正極活物質板２２の気孔率は、例えば、２５％～４５％である。正極活物質板２２の気孔率とは、正極活物質板２２における気孔（開気孔および閉気孔を含む。）の体積比率である。当該気孔率は、正極活物質板２２の断面のＳＥＭ画像を解析することにより測定することができる。例えば、正極活物質板２２をクロスセクションポリッシャ（ＣＰ）で加工して研磨断面を露出させる。当該研磨断面を所定の倍率（例えば、１０００倍）および所定の視野（例えば、１２５μｍ×１２５μｍ）でＳＥＭにより観察する。得られたＳＥＭ画像を解析し、視野内の全ての気孔の面積を視野内の正極活物質板２２の面積（断面積）で除算し、得られた値に１００を乗算することにより気孔率（％）を得る。 The porosity of the positive electrode active material plate 22 is, for example, 25% to 45%. The porosity of the positive electrode active material plate 22 is a volume ratio of pores (including open pores and closed pores) in the positive electrode active material plate 22. The porosity can be measured by analyzing a SEM image of the cross section of the positive electrode active material plate 22. For example, the positive electrode active material plate 22 is processed by a cross section polisher (CP) to expose a polished cross section. The polished cross section is observed by SEM with a predetermined magnification (for example, 1000 times) and a predetermined visual field (for example, 125 μm×125 μm). The obtained SEM image is analyzed, the area of all pores in the visual field is divided by the area (cross-sectional area) of the positive electrode active material plate 22 in the visual field, and the obtained value is multiplied by 100 to obtain the porosity ( %).
　正極活物質板２２に含まれる気孔の直径の平均値である平均気孔径は、例えば１５μｍ以下であり、好ましくは１２μｍ以下であり、より好ましくは１０μｍ以下である。また、当該平均気孔径は、例えば０．１μｍ以上であり、好ましくは０．３μｍ以上である。上述の気孔の直径は、典型的には、当該気孔を同体積あるいは同断面積を有する球形と仮定した場合の、当該球形における直径である。平均気孔径は、複数の気孔の直径の平均値を個数基準で算出したものである。当該平均気孔径は、例えば、断面ＳＥＭ画像の解析、または、水銀圧入法等、周知の方法により求めることができる。好ましくは、当該平均気孔径は、水銀ポロシメーターを用いて水銀圧入法により測定される。 The average pore diameter, which is the average value of the diameter of the pores included in the positive electrode active material plate 22, is, for example, 15 μm or less, preferably 12 μm or less, and more preferably 10 μm or less. The average pore diameter is, for example, 0.1 μm or more, preferably 0.3 μm or more. The diameter of the pores described above is typically the diameter of the sphere when the pores are assumed to be spherical with the same volume or the same cross-sectional area. The average pore diameter is an average value of the diameters of a plurality of pores calculated on a number basis. The average pore diameter can be obtained by a known method such as analysis of a cross-sectional SEM image or mercury porosimetry. Preferably, the average pore diameter is measured by a mercury porosimetry method using a mercury porosimeter.
　図１に示す例では、正極活物質板２２は、１枚の板状部材であるが、複数の板状部材（以下、「活物質板要素」と呼ぶ。）に分割されていてもよい。この場合、複数の活物質板要素はそれぞれ、導電性接合層２３を介して正極集電体２１に接合される。複数の活物質板要素は、例えば、正極集電体２１上においてマトリクス状（すなわち、格子状）に配列される。平面視における各活物質板要素の形状は、例えば略矩形である。複数の活物質板要素は、平面視において略同形状（すなわち、略同じ形かつ略同じ大きさ）であってもよく、異なる形状を有していてもよい。複数の活物質板要素は、平面視において互いに離間して配置される。 In the example shown in FIG. 1, the positive electrode active material plate 22 is a single plate-shaped member, but it may be divided into a plurality of plate-shaped members (hereinafter referred to as “active material plate elements”). In this case, each of the plurality of active material plate elements is bonded to the positive electrode current collector 21 via the conductive bonding layer 23. The plurality of active material plate elements are arranged in a matrix (that is, a grid) on the positive electrode current collector 21, for example. The shape of each active material plate element in a plan view is, for example, a substantially rectangular shape. The plurality of active material plate elements may have substantially the same shape (that is, substantially the same shape and substantially the same size) in plan view, or may have different shapes. The plurality of active material plate elements are arranged apart from each other in a plan view.
　導電性接合層２３は、導電性粉末と、バインダとを含む。導電性粉末は、例えば、アセチレンブラック、鱗片状の天然黒鉛、カーボンナノチューブ、カーボンナノファイバー、カーボンナノチューブ誘導体、または、カーボンナノファイバー誘導体等の粉末である。バインダは、例えば、ポリイミドアミド樹脂を含む。バインダに含まれるポリイミドアミド樹脂は、１種類であっても、２種類以上であってもよい。また、バインダは、ポリイミドアミド樹脂以外の樹脂を含んでいてもよい。導電性接合層２３は、上述の導電性粉末およびバインダ、並びに、溶媒を含む液状またはペースト状の接着剤が、正極集電体２１または正極活物質板２２に塗布されて、正極集電体２１と正極活物質板２２との間にて溶媒が蒸発して固化することにより形成される。 The conductive bonding layer 23 contains conductive powder and a binder. The conductive powder is, for example, powder of acetylene black, scaly natural graphite, carbon nanotubes, carbon nanofibers, carbon nanotube derivatives, or carbon nanofiber derivatives. The binder includes, for example, a polyimide amide resin. The polyimide amide resin contained in the binder may be one type or two or more types. Further, the binder may contain a resin other than the polyimide amide resin. The conductive bonding layer 23 is formed by coating the positive electrode current collector 21 or the positive electrode active material plate 22 with a liquid or paste adhesive containing the above-described conductive powder and binder, and a solvent. And the positive electrode active material plate 22 are formed by evaporating and solidifying the solvent.
　正極集電体２１の厚さは、例えば９μｍ～５０μｍであり、好ましくは９μｍ～２０μｍであり、より好ましくは９μｍ～１５μｍである。正極活物質板２２の厚さは、例えば１５μｍ～２００μｍであり、好ましくは３０μｍ～１５０μｍであり、より好ましくは５０μｍ～１００μｍである。正極活物質板２２を厚くすることにより、単位面積当たりの活物質容量を大きくし、リチウム二次電池１のエネルギー密度を増大させることができる。正極活物質板２２を薄くすることにより、充放電の繰り返しに伴う電池特性の劣化（特に、抵抗値の増大）を抑制することができる。導電性接合層２３の厚さは、例えば、３μｍ～２８μｍであり、好ましくは５μｍ～２５μｍである。 The thickness of the positive electrode current collector 21 is, for example, 9 μm to 50 μm, preferably 9 μm to 20 μm, and more preferably 9 μm to 15 μm. The thickness of the positive electrode active material plate 22 is, for example, 15 μm to 200 μm, preferably 30 μm to 150 μm, and more preferably 50 μm to 100 μm. By thickening the positive electrode active material plate 22, the active material capacity per unit area can be increased and the energy density of the lithium secondary battery 1 can be increased. By thinning the positive electrode active material plate 22, it is possible to suppress deterioration of battery characteristics (in particular, increase in resistance value) due to repeated charging and discharging. The thickness of the conductive bonding layer 23 is, for example, 3 μm to 28 μm, preferably 5 μm to 25 μm.
　負極３は、負極集電体３１と、負極活物質層３２とを備える。負極集電体３１は、導電性を有するシート状の部材である。負極集電体３１の上面は、負極接合層６４を介して外装体６に接合されている。負極接合層６４は、例えば、酸変性ポリオレフィン系樹脂とエポキシ系樹脂との混合樹脂により形成される。負極接合層６４は、他の様々な材料により形成されてもよい。負極接合層６４の厚さは、例えば０．５μｍ～１０μｍである。 The negative electrode 3 includes a negative electrode current collector 31 and a negative electrode active material layer 32. The negative electrode current collector 31 is a conductive sheet-shaped member. The upper surface of the negative electrode current collector 31 is bonded to the exterior body 6 via the negative electrode bonding layer 64. The negative electrode bonding layer 64 is formed of, for example, a mixed resin of acid-modified polyolefin resin and epoxy resin. The negative electrode bonding layer 64 may be formed of various other materials. The thickness of the negative electrode bonding layer 64 is, for example, 0.5 μm to 10 μm.
　負極集電体３１は、例えば、銅等の金属により形成される金属箔である。当該金属箔は、銅以外の様々な金属（例えば、銅、ステンレス鋼、ニッケル、アルミニウム、銀、金、クロム、鉄、スズ、鉛、タングステン、モリブデン、チタン、亜鉛、または、これらを含む合金等）により形成されてもよい。 The negative electrode current collector 31 is, for example, a metal foil formed of a metal such as copper. The metal foil is various metals other than copper (for example, copper, stainless steel, nickel, aluminum, silver, gold, chromium, iron, tin, lead, tungsten, molybdenum, titanium, zinc, or alloys containing these, etc.). ).
　負極活物質層３２は、樹脂を主成分とするバインダと、負極活物質である炭素質材料とを含む。負極活物質層３２は、負極集電体３１の下面上に塗工される。すなわち、負極３は、いわゆる塗工電極である。負極活物質層３２は、上下方向においてセパレータ４と対向する。負極活物質層３２の下面は、セパレータ４の上面と接触する。負極活物質層３２では、上述の炭素質材料は、例えば、黒鉛（天然黒鉛もしくは人造黒鉛）、熱分解炭素、コークス、樹脂焼成体、メソフェーズ小球体、または、メソフェーズ系ピッチ等である。負極３では、炭素質材料に代えてリチウム吸蔵物質が負極活物質として利用されてもよい。当該リチウム吸蔵物質は、例えば、シリコン、アルミ、スズ、鉄、イリジウム、または、これらを含む合金、酸化物もしくはフッ化物等である。 The negative electrode active material layer 32 includes a binder containing a resin as a main component and a carbonaceous material that is a negative electrode active material. The negative electrode active material layer 32 is coated on the lower surface of the negative electrode current collector 31. That is, the negative electrode 3 is a so-called coated electrode. The negative electrode active material layer 32 faces the separator 4 in the vertical direction. The lower surface of the negative electrode active material layer 32 contacts the upper surface of the separator 4. In the negative electrode active material layer 32, the above-mentioned carbonaceous material is, for example, graphite (natural graphite or artificial graphite), pyrolytic carbon, coke, resin fired body, mesophase spherule, or mesophase pitch. In the negative electrode 3, a lithium storage material may be used as the negative electrode active material instead of the carbonaceous material. The lithium storage material is, for example, silicon, aluminum, tin, iron, iridium, or an alloy, oxide, or fluoride containing these.
　バインダは、例えば、スチレンブタジエンゴム（ＳＢＲ）、ポリフッ化ビニリデン（ＰＶＤＦ）またはこれらの混合物である。本実施の形態では、ＳＢＲがバインダとして使用される。ＳＢＲは、ＰＶＤＦに比べて、後述する電解液５に含まれるγ－ブチロラクトン（ＧＢＬ）に溶解しにくい。したがって、ＳＢＲを負極３のバインダとして使用することにより、電解液５による負極活物質層３２の劣化を抑制することができる。 The binder is, for example, styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF) or a mixture thereof. In this embodiment, SBR is used as a binder. Compared to PVDF, SBR is less likely to dissolve in γ-butyrolactone (GBL) contained in the electrolytic solution 5 described later. Therefore, by using SBR as the binder of the negative electrode 3, the deterioration of the negative electrode active material layer 32 due to the electrolytic solution 5 can be suppressed.
　負極集電体３１の厚さは、例えば５μｍ～２５μｍであり、好ましくは８μｍ～２０μｍであり、より好ましくは８μｍ～１５μｍである。負極活物質層３２の厚さは、例えば２０μｍ～３００μｍであり、好ましくは３０μｍ～２５０μｍであり、より好ましくは３０μｍ～１５０μｍである。負極活物質層３２を厚くすることにより、単位面積当たりの活物質容量を大きくし、リチウム二次電池１のエネルギー密度を増大させることができる。負極活物質層３２を薄くすることにより、充放電の繰り返しに伴う電池特性の劣化（特に、抵抗値の増大）を抑制することができる。 The thickness of the negative electrode current collector 31 is, for example, 5 μm to 25 μm, preferably 8 μm to 20 μm, and more preferably 8 μm to 15 μm. The thickness of the negative electrode active material layer 32 is, for example, 20 μm to 300 μm, preferably 30 μm to 250 μm, and more preferably 30 μm to 150 μm. By thickening the negative electrode active material layer 32, the active material capacity per unit area can be increased and the energy density of the lithium secondary battery 1 can be increased. By thinning the negative electrode active material layer 32, it is possible to suppress deterioration of battery characteristics (in particular, increase in resistance value) due to repeated charging and discharging.
　リチウム二次電池１では、塗工電極である負極３に代えて、図３に示すように、負極３とは異なる構造を有する負極３ａが設けられてもよい。負極３ａは、上述の正極２と略同様の構造を有する。具体的には、負極３ａは、負極集電体３１ａと、負極活物質板３２ａと、導電性接合層３３ａとを備える。負極集電体３１ａは、導電性を有するシート状の部材である。負極集電体３１ａは、例えば、上述の負極集電体３１と同様の材料にて形成された同構造の部材である。 The lithium secondary battery 1 may be provided with a negative electrode 3a having a structure different from that of the negative electrode 3, as shown in FIG. 3, instead of the negative electrode 3 which is a coating electrode. The negative electrode 3a has substantially the same structure as the positive electrode 2 described above. Specifically, the negative electrode 3a includes a negative electrode current collector 31a, a negative electrode active material plate 32a, and a conductive bonding layer 33a. The negative electrode current collector 31a is a sheet-shaped member having conductivity. The negative electrode current collector 31a is, for example, a member having the same structure and made of the same material as the negative electrode current collector 31 described above.
　負極活物質板３２ａ（すなわち、負極３ａの活物質板）は、リチウム複合酸化物（例えば、リチウムチタン酸化物（ＬＴＯ））を含む比較的薄い板状セラミック焼結体である。負極活物質板３２ａは、導電性接合層３３ａを介して負極集電体３１ａの下面に接合される。導電性接合層３３ａは、例えば、上述の正極２の導電性接合層２３と同様の材料により形成される。負極活物質板３２ａは、上下方向においてセパレータ４と対向する。負極活物質板３２ａの下面は、セパレータ４の上面と接触する。負極活物質板３２ａは、正極活物質板２２と同様に、実質的に樹脂を含んでいない。したがって、負極３ａのセパレータ４に対向する主面（すなわち、図３中の下面）は、実質的に樹脂を含んでいない。 The negative electrode active material plate 32a (that is, the active material plate of the negative electrode 3a) is a relatively thin plate-shaped ceramic sintered body containing a lithium composite oxide (for example, lithium titanium oxide (LTO)). The negative electrode active material plate 32a is bonded to the lower surface of the negative electrode current collector 31a via the conductive bonding layer 33a. The conductive bonding layer 33a is formed of, for example, the same material as the conductive bonding layer 23 of the positive electrode 2 described above. The negative electrode active material plate 32a faces the separator 4 in the vertical direction. The lower surface of the negative electrode active material plate 32 a contacts the upper surface of the separator 4. The negative electrode active material plate 32 a, like the positive electrode active material plate 22, contains substantially no resin. Therefore, the main surface of the negative electrode 3a facing the separator 4 (that is, the lower surface in FIG. 3) contains substantially no resin.
　負極集電体３１の厚さは、例えば５μｍ～２５μｍであり、好ましくは８μｍ～２０μｍであり、より好ましくは８μｍ～１５μｍである。負極活物質板３２ａの厚さは、例えば１０μｍ～３００μｍであり、好ましくは３０μｍ～２００μｍであり、より好ましくは３０μｍ～１５０μｍである。負極活物質板３２ａを厚くすることにより、単位面積当たりの活物質容量を大きくし、リチウム二次電池１のエネルギー密度を増大させることができる。負極活物質板３２ａを薄くすることにより、充放電の繰り返しに伴う電池特性の劣化（特に、抵抗値の増大）を抑制することができる。導電性接合層３３ａの厚さは、例えば、３μｍ～３０μｍであり、好ましくは５μｍ～２５μｍである。 The thickness of the negative electrode current collector 31 is, for example, 5 μm to 25 μm, preferably 8 μm to 20 μm, and more preferably 8 μm to 15 μm. The thickness of the negative electrode active material plate 32a is, for example, 10 μm to 300 μm, preferably 30 μm to 200 μm, and more preferably 30 μm to 150 μm. By thickening the negative electrode active material plate 32a, the active material capacity per unit area can be increased and the energy density of the lithium secondary battery 1 can be increased. By thinning the negative electrode active material plate 32a, it is possible to suppress deterioration of battery characteristics (in particular, increase in resistance value) due to repeated charging and discharging. The thickness of the conductive bonding layer 33a is, for example, 3 μm to 30 μm, preferably 5 μm to 25 μm.
　図３に示す例では、負極活物質板３２ａは、１枚の板状部材であるが、複数の板状部材（以下、「活物質板要素」と呼ぶ。）に分割されていてもよい。この場合、複数の活物質板要素はそれぞれ、導電性接合層３３ａを介して負極集電体３１ａに接合される。複数の活物質板要素は、例えば、負極集電体３１ａ上においてマトリクス状（すなわち、格子状）に配列される。平面視における各活物質板要素の形状は、例えば略矩形である。複数の活物質板要素は、平面視において略同形状（すなわち、略同じ形かつ略同じ大きさ）であってもよく、異なる形状を有していてもよい。複数の活物質板要素は、平面視において互いに離間して配置される。 In the example shown in FIG. 3, the negative electrode active material plate 32a is a single plate-shaped member, but may be divided into a plurality of plate-shaped members (hereinafter referred to as “active material plate elements”). In this case, each of the plurality of active material plate elements is bonded to the negative electrode current collector 31a via the conductive bonding layer 33a. For example, the plurality of active material plate elements are arranged in a matrix (that is, a grid) on the negative electrode current collector 31a. The shape of each active material plate element in a plan view is, for example, a substantially rectangular shape. The plurality of active material plate elements may have substantially the same shape (that is, substantially the same shape and substantially the same size) in plan view, or may have different shapes. The plurality of active material plate elements are arranged apart from each other in a plan view.
　図１および図３に示すリチウム二次電池１では、電解液５は、例えば、非水溶媒中にホウフッ化リチウム（ＬｉＢＦ４）を溶解させた溶液である。非水溶媒は、γ－ブチロラクトン（ＧＢＬ）からなる単独溶媒であってもよいし、ＧＢＬおよびエチレンカーボネート（ＥＣ）を含む混合溶媒であってもよい。非水溶媒にＧＢＬが含まれることにより、電解液５の沸点が上昇するため、リチウム二次電池１の耐熱性を向上させることができる。リチウム二次電池１の耐熱性向上の観点からは、当該非水溶媒におけるＥＣ：ＧＢＬの体積比は、例えば０：１～１：１（すなわち、ＧＢＬ比率５０体積％～１００体積％）であり、好ましくは０：１～１：１．５（ＧＢＬ比率６０体積％～１００体積％）であり、より好ましくは０：１～１：２（ＧＢＬ比率６６．６体積％～１００体積％）であり、さらに好ましくは０：１～１：３（ＧＢＬ比率７５体積％～１００体積％）である。なお、電解液５の溶媒は、様々に変更されてよい。例えば、電解液５の溶媒は、必ずしもＧＢＬを含む必要はなく、ＥＣの単独溶媒であってもよい。 In the lithium secondary battery 1 shown in FIGS. 1 and 3, the electrolytic solution 5 is, for example, a solution in which lithium borofluoride (LiBF 4 ) is dissolved in a non-aqueous solvent. The non-aqueous solvent may be a single solvent consisting of γ-butyrolactone (GBL) or a mixed solvent containing GBL and ethylene carbonate (EC). By including GBL in the non-aqueous solvent, the boiling point of the electrolytic solution 5 rises, so that the heat resistance of the lithium secondary battery 1 can be improved. From the viewpoint of improving the heat resistance of the lithium secondary battery 1, the volume ratio of EC:GBL in the non-aqueous solvent is, for example, 0:1 to 1:1 (that is, the GBL ratio is 50% to 100% by volume). , Preferably 0:1 to 1:1.5 (GBL ratio 60% by volume to 100% by volume), and more preferably 0:1 to 1:2 (GBL ratio 66.6% by volume to 100% by volume). And more preferably 0:1 to 1:3 (GBL ratio 75% to 100% by volume). The solvent of the electrolytic solution 5 may be changed variously. For example, the solvent of the electrolytic solution 5 does not necessarily need to contain GBL and may be a single solvent of EC.
　溶質であるＬｉＢＦ４は、分解温度の高い電解質である。このため、リチウム二次電池１の耐熱性をさらに向上させることができる。電解液５におけるＬｉＢＦ４濃度は、例えば０．５ｍｏｌ／Ｌ～２ｍｏｌ／Ｌであり、好ましくは０．６ｍｏｌ／Ｌ～１．９ｍｏｌ／Ｌであり、より好ましくは０．７ｍｏｌ／Ｌ～１．７ｍｏｌ／Ｌであり、さらに好ましくは０．８ｍｏｌ／Ｌ～１．５ｍｏｌ／Ｌである。なお、電解液５の溶質は、様々に変更されてよい。例えば、電解液５の溶質は、六フッ化リン酸リチウム（ＬｉＰＦ６）であってもよい。 LiBF 4 , which is a solute, is an electrolyte having a high decomposition temperature. Therefore, the heat resistance of the lithium secondary battery 1 can be further improved. The LiBF 4 concentration in the electrolytic solution 5 is, for example, 0.5 mol/L to 2 mol/L, preferably 0.6 mol/L to 1.9 mol/L, and more preferably 0.7 mol/L to 1.7 mol. /L, and more preferably 0.8 mol/L to 1.5 mol/L. The solute of the electrolytic solution 5 may be variously changed. For example, the solute of the electrolytic solution 5 may be lithium hexafluorophosphate (LiPF 6 ).
　電解液５は、添加剤としてビニレンカーボネート（ＶＣ）、および／または、フルオロエチレンカーボネート（ＦＥＣ）をさらに含むのが好ましい。ＶＣおよびＦＥＣはいずれも耐熱性に優れる。電解液５が当該添加剤を含むことにより、耐熱性に優れたＳＥＩ膜が負極３の表面に形成され、リチウム二次電池１の耐熱性を、より一層向上することができる。 The electrolytic solution 5 preferably further contains vinylene carbonate (VC) and/or fluoroethylene carbonate (FEC) as an additive. Both VC and FEC have excellent heat resistance. When the electrolytic solution 5 contains the additive, a SEI film having excellent heat resistance is formed on the surface of the negative electrode 3, and the heat resistance of the lithium secondary battery 1 can be further improved.
　セパレータ４は、シート状または薄板状の絶縁部材である。セパレータ４は、例えば、樹脂により形成された単層セパレータである。換言すれば、セパレータ４の正極２に対向する面および負極３に対向する面は、樹脂により形成されている。当該樹脂は、例えば、ポリイミド、ポリエチレン、ポリエステル（例えば、ポリエチレンテレフタレート（ＰＥＴ））またはポリプロピレン等である。本実施の形態では、セパレータ４はポリイミド製の多孔質膜（例えば、三次元多孔構造体（３ＤＯＭ））である。ポリイミドは、ポリエチレンおよびポリプロピレンに比べて、耐熱性に優れ、また、上述のＧＢＬに対する濡れ性にも優れる。したがって、ポリイミド製のセパレータ４を使用することにより、リチウム二次電池１の耐熱性を向上することができる。また、電解液５がセパレータ４により弾かれることを抑制し、電解液５をセパレータ４に容易に浸透させることができる。 The separator 4 is a sheet-shaped or thin plate-shaped insulating member. The separator 4 is, for example, a single-layer separator made of resin. In other words, the surface of the separator 4 facing the positive electrode 2 and the surface of the separator 4 facing the negative electrode 3 are made of resin. The resin is, for example, polyimide, polyethylene, polyester (for example, polyethylene terephthalate (PET)), polypropylene, or the like. In the present embodiment, the separator 4 is a polyimide porous film (for example, a three-dimensional porous structure (3DOM)). Polyimide is superior in heat resistance to polyethylene and polypropylene, and is also excellent in wettability with GBL. Therefore, the heat resistance of the lithium secondary battery 1 can be improved by using the separator 4 made of polyimide. Further, the electrolytic solution 5 can be prevented from being repelled by the separator 4, and the electrolytic solution 5 can easily permeate into the separator 4.
　なお、セパレータ４は、例えば、セラミック基板上に樹脂層が積層された２層セパレータであってもよい。あるいは、セパレータ４は、樹脂層である基板上にセラミックがコーティングされた２層セパレータであってもよい。セパレータ４は、３層以上の多層構造を有していてもよい。例えば、セパレータ４は、セラミック基板の上面および下面に樹脂層が積層された３層セパレータであってもよい。 Note that the separator 4 may be, for example, a two-layer separator in which a resin layer is laminated on a ceramic substrate. Alternatively, the separator 4 may be a two-layer separator in which a substrate, which is a resin layer, is coated with ceramic. The separator 4 may have a multilayer structure of three layers or more. For example, the separator 4 may be a three-layer separator in which resin layers are laminated on the upper surface and the lower surface of the ceramic substrate.
　図４は、図２中のＩＶ－ＩＶの位置でリチウム二次電池１を切断した断面図である。図５は、図４中のリチウム二次電池１の左端部を拡大して示す図である。図４および図５では、図の理解を容易にするために、リチウム二次電池１およびその構成を、実際よりも厚く描いている。また、外装体６については、ラミネート構造の詳細な図示を省略し、１本の実線で描いている。図６は、リチウム二次電池１の平面図である。 FIG. 4 is a cross-sectional view of the lithium secondary battery 1 taken along the line IV-IV in FIG. FIG. 5 is an enlarged view showing the left end portion of the lithium secondary battery 1 in FIG. In FIG. 4 and FIG. 5, the lithium secondary battery 1 and its configuration are drawn thicker than they actually are in order to facilitate understanding of the drawings. Further, with respect to the exterior body 6, the detailed illustration of the laminated structure is omitted, and it is drawn by one solid line. FIG. 6 is a plan view of the lithium secondary battery 1.
　図４ないし図６に示すように、外装体６は、被覆領域６７と、外周領域６８とを備える。また、外周領域６８は、第１領域６８１と、第２領域６８２とを備える。図４および図６に示す例では、外周領域６８は２つの第１領域６８１と、２つの第２領域６８２とを備える。図６では、被覆領域６７、第１領域６８１および第２領域６８２をそれぞれ二点鎖線にて囲む。また、図６では、被覆領域６７、および、外周領域６８の第２領域６８２を除く領域に平行斜線を付す。外周領域６８の第２領域６８２には平行斜線を付していない。 As shown in FIGS. 4 to 6, the outer casing 6 includes a covering region 67 and an outer peripheral region 68. In addition, the outer peripheral area 68 includes a first area 681 and a second area 682. In the example shown in FIGS. 4 and 6, the outer peripheral area 68 includes two first areas 681 and two second areas 682. In FIG. 6, the covering region 67, the first region 681, and the second region 682 are each surrounded by a chain double-dashed line. In addition, in FIG. 6, the hatched area 67 and the area of the outer peripheral area 68 excluding the second area 682 are hatched in parallel. The second area 682 of the outer peripheral area 68 is not shaded with parallel diagonal lines.
　外装体６の被覆領域６７は、平面視において、正極２、セパレータ４および負極３と上下方向に重なる略矩形状の領域である。外周領域６８は、外装体６のうち被覆領域６７を除く領域（すなわち、正極２、セパレータ４および負極３と重ならない領域）であり、平面視において、被覆領域６７の周囲を囲む略矩形枠状の領域である。外周領域６８は、被覆領域６７と連続する。 The covering region 67 of the outer package 6 is a substantially rectangular region that vertically overlaps the positive electrode 2, the separator 4, and the negative electrode 3 in a plan view. The outer peripheral region 68 is a region (that is, a region that does not overlap the positive electrode 2, the separator 4, and the negative electrode 3) of the exterior body 6 excluding the coating region 67, and has a substantially rectangular frame shape surrounding the periphery of the coating region 67 in plan view. Area. The outer peripheral area 68 is continuous with the covered area 67.
　２つの第１領域６８１は、図４および図６中の左右方向の両側の一対の辺（以下、「長辺６９１」とも呼ぶ。）に沿ってそれぞれ延びる略矩形の略帯状領域である。以下の説明では、図４ないし図６中の左右方向を「幅方向」とも呼ぶ。当該幅方向は、外装体６の一対の長辺６９１に対して略垂直である。各第１領域６８１は、長辺６９１を含む領域であり、被覆領域６７の幅方向の一対の辺から幅方向に離間している。一対の第１領域６８１では、上下方向に重なる外装体６の２層のシート部（すなわち、第１シート部６５および第２シート部６６）が、上述のように接合されている。 The two first regions 681 are substantially rectangular strip-shaped regions that extend along a pair of sides on both sides in the left-right direction in FIGS. 4 and 6 (hereinafter, also referred to as “long sides 691”). In the following description, the left-right direction in FIGS. 4 to 6 is also referred to as “width direction”. The width direction is substantially perpendicular to the pair of long sides 691 of the exterior body 6. Each first region 681 is a region including a long side 691, and is separated in the width direction from a pair of sides in the width direction of the covering region 67. In the pair of first regions 681, the two-layer sheet portions (that is, the first sheet portion 65 and the second sheet portion 66) of the exterior body 6 that overlap in the vertical direction are joined as described above.
　図６に示す例では、各第１領域６８１の幅方向に対して垂直な方向（以下、「長手方向」とも呼ぶ。）の長さは、被覆領域６７の長手方向の長さと略同じである。また、各第１領域６８１の幅方向の幅（以下、単に「幅」とも呼ぶ。）は、長手方向の略全長に亘って略一定である。第１領域６８１の幅は、例えば１ｍｍ～５ｍｍであり、好ましくは１．５ｍｍ～４ｍｍであり、より好ましくは２ｍｍ～３ｍｍである。なお、第１領域６８１は、実質的に帯状と捉えられる形状を有していればよく、第１領域６８１の幅は長手方向において多少変化してもよい。 In the example shown in FIG. 6, the length of each first region 681 in the direction perpendicular to the width direction (hereinafter, also referred to as “longitudinal direction”) is substantially the same as the length of the covered region 67 in the longitudinal direction. .. The width of each first region 681 in the width direction (hereinafter, also simply referred to as “width”) is substantially constant over the entire length in the longitudinal direction. The width of the first region 681 is, for example, 1 mm to 5 mm, preferably 1.5 mm to 4 mm, and more preferably 2 mm to 3 mm. The first region 681 only needs to have a shape that can be regarded as a substantially strip shape, and the width of the first region 681 may change slightly in the longitudinal direction.
　２つの第２領域６８２は、被覆領域６７の幅方向の両側にて、被覆領域６７と一対の第１領域６８１との間に配置される。２つの第２領域６８２は、被覆領域６７の幅方向の一対の辺に沿って長手方向に延びる略矩形の略帯状領域である。換言すれば、２つの第２領域６８２は、一対の第１領域６８１に沿って長手方向に延びる略矩形の略帯状領域である。各第２領域６８２は、幅方向において被覆領域６７および第１領域６８１と連続している。第２領域６８２では、上下方向に重なる外装体６の２層のシート部（すなわち、第１シート部６５および第２シート部６６）が、非接合状態にて接触している。当該接触は、第１シート部６５と第２シート部６６との間に電解液５等が介在しない直接的接触である。なお、第２領域６８２では、第１シート部６５および第２シート部６６は、僅かな空隙を挟んで近接していてもよい。当該空隙には、電解液５が僅かに存在していてもよく、電解液５が存在していなくてもよい。 The two second regions 682 are arranged between the covering region 67 and the pair of first regions 681 on both sides of the covering region 67 in the width direction. The two second regions 682 are substantially rectangular strip-shaped regions extending in the longitudinal direction along a pair of sides of the covering region 67 in the width direction. In other words, the two second regions 682 are substantially rectangular strip-shaped regions extending in the longitudinal direction along the pair of first regions 681. Each second region 682 is continuous with the covering region 67 and the first region 681 in the width direction. In the second region 682, the two-layer sheet portions (that is, the first sheet portion 65 and the second sheet portion 66) of the exterior body 6 that are vertically overlapped are in contact with each other in a non-bonded state. The contact is a direct contact in which the electrolytic solution 5 and the like are not interposed between the first sheet portion 65 and the second sheet portion 66. In the second region 682, the first sheet portion 65 and the second sheet portion 66 may be close to each other with a slight gap therebetween. The electrolyte solution 5 may be slightly present in the void, or the electrolyte solution 5 may not be present.
　図６に示す例では、各第２領域６８２の長手方向の長さは、被覆領域６７および第１領域６８１の長手方向の長さと略同じである。また、各第２領域６８２の幅方向の幅は、長手方向の略全長に亘って略一定である。第２領域６８２の幅は、例えば０．３ｍｍ～２５ｍｍであり、好ましくは０．５ｍｍ～１５ｍｍであり、より好ましくは１ｍｍ～５ｍｍである。なお、第２領域６８２は、実質的に帯状と捉えられる形状を有していればよく、第２領域６８２の幅は長手方向において多少変化してもよい。 In the example shown in FIG. 6, the length of each second region 682 in the longitudinal direction is substantially the same as the length of the covering region 67 and the first region 681 in the longitudinal direction. The width of each second region 682 in the width direction is substantially constant over the entire length in the longitudinal direction. The width of the second region 682 is, for example, 0.3 mm to 25 mm, preferably 0.5 mm to 15 mm, and more preferably 1 mm to 5 mm. The second region 682 only needs to have a shape that can be regarded as a substantially strip shape, and the width of the second region 682 may change slightly in the longitudinal direction.
　以下の説明では、幅方向に並ぶ一対の第２領域６８２の合計幅を「第２領域幅Ａ１」と呼ぶ。また、正極２の正極活物質板２２の幅（すなわち、正極２において活物質が設けられる活物質領域の幅）を「正極活物質幅」と呼び、負極３の負極活物質層３２の幅（すなわち、負極３において活物質が設けられる活物質領域の幅）を「負極活物質幅」と呼ぶ。正極活物質幅と負極活物質幅とが異なる場合、正極活物質幅および負極活物質幅のうち小さい方の幅を「活物質領域幅Ｂ３」と呼ぶ。一方、正極活物質幅と負極活物質幅とが同じである場合は、正極活物質幅および負極活物質幅のうちいずれか一方を活物質領域幅Ｂ３とする。図４に示す例では、正極活物質板２２の幅は、負極活物質層３２の幅と略同じである。この場合、活物質領域幅Ｂ３は、正極活物質幅および負極活物質幅のいずれであってもよい。 In the following description, the total width of the pair of second areas 682 arranged in the width direction is referred to as “second area width A1”. Further, the width of the positive electrode active material plate 22 of the positive electrode 2 (that is, the width of the active material region in which the active material is provided in the positive electrode 2) is referred to as the “positive electrode active material width”, and the width of the negative electrode active material layer 32 of the negative electrode 3 ( That is, the width of the active material region in which the active material is provided in the negative electrode 3) is called the “negative electrode active material width”. When the positive electrode active material width and the negative electrode active material width are different, the smaller width of the positive electrode active material width and the negative electrode active material width is referred to as “active material region width B3”. On the other hand, when the positive electrode active material width and the negative electrode active material width are the same, one of the positive electrode active material width and the negative electrode active material width is set as the active material region width B3. In the example shown in FIG. 4, the width of the positive electrode active material plate 22 is substantially the same as the width of the negative electrode active material layer 32. In this case, the active material region width B3 may be either the positive electrode active material width or the negative electrode active material width.
　第２領域幅Ａ１を被除数とし、活物質領域幅Ｂ３を除数として、被除数を除数により除算した値（すなわち、第２領域幅Ａ１／活物質領域幅Ｂ３）は、例えば０．０２以上であり、好ましくは０．０４以上である。また、第２領域幅Ａ１／活物質領域幅Ｂ３は、例えば１以下であり、好ましくは０．２以下である。活物質領域幅Ｂ３は、例えば、１５ｍｍ～２５ｍｍである。 A value obtained by dividing the dividend by the divisor with the second region width A1 as the dividend and the active material region width B3 as the divisor (that is, the second region width A1/active material region width B3) is, for example, 0.02 or more, It is preferably 0.04 or more. The second region width A1/active material region width B3 is, for example, 1 or less, preferably 0.2 or less. The active material region width B3 is, for example, 15 mm to 25 mm.
　リチウム二次電池１の外装体６では、第２領域６８２は、必ずしも被覆領域６７の幅方向の両側に設けられる必要はなく、被覆領域６７の幅方向の一方側のみに配置されてもよい。換言すれば、第２領域６８２は、一対の第１領域６８１のうち、少なくとも一方の第１領域６８１と被覆領域６７との間に設けられていればよい。外装体６において、一対の第１領域６８１のうち一方の第１領域６８１と被覆領域６７との間にのみ第２領域６８２が存在する場合、上述の第２領域幅Ａ１は、当該１つの第２領域６８２の幅である。 In the exterior body 6 of the lithium secondary battery 1, the second regions 682 do not necessarily have to be provided on both sides of the covering region 67 in the width direction, and may be arranged only on one side of the covering region 67 in the width direction. In other words, the second region 682 may be provided between at least one of the pair of first regions 681 and the covering region 67. In the exterior body 6, when the second region 682 exists only between the one first region 681 and the covering region 67 of the pair of first regions 681, the above-mentioned second region width A1 is the same as the one of the first region 681. This is the width of the two areas 682.
　図４に示す例では、外装体６の幅方向両端部において、第１領域６８１および第２領域６８２は、折り曲げられることなく幅方向に略平行に延びているが、第１領域６８１の形状は様々に変更されてよい。例えば、図７ないし図９に示すように、外装体６の第１領域６８１は、外装体６の一対の長辺６９１（図６参照）に平行に延びる折り返し線６９３にて、幅方向内側（すなわち、被覆領域６７に近づく側）へと約１８０°折り返されている。以下の説明では、外周領域６８のうち、被覆領域６７から折り返し線６９３まで延びる部位を「非折り返し部６９４」と呼び、折り返し線６９３にて幅方向内側に折り返される部位を「折り返し部６９５」と呼ぶ。折り返し部６９５は、非折り返し部６９４と上下方向に対向する。 In the example shown in FIG. 4, the first region 681 and the second region 682 extend substantially parallel to the width direction at both ends of the exterior body 6 in the width direction, but the shape of the first region 681 is It may be changed in various ways. For example, as shown in FIGS. 7 to 9, the first region 681 of the exterior body 6 has a fold line 693 extending in parallel to the pair of long sides 691 (see FIG. 6) of the exterior body 6 in the width direction inside ( That is, it is folded back by about 180° to the side closer to the covering region 67). In the following description, a part of the outer peripheral region 68 extending from the covering region 67 to the folding line 693 is referred to as a “non-folding part 694”, and a part folded back inward in the width direction at the folding line 693 is referred to as a “folding part 695”. Call. The folded portion 695 faces the non-folded portion 694 in the vertical direction.
　図７ないし図９に示す例では、折り返し部６９５は図中の上側（すなわち、負極３側）へと折り返されているが、図中の下側（すなわち、正極２側）へと折り返されてもよい。なお、図７ないし図９では、幅方向の一方側の第１領域６８１および第２領域６８２を示しているが、幅方向の他方側の第１領域６８１および第２領域６８２も、同様の構造を有してよい。 In the example shown in FIGS. 7 to 9, the folded portion 695 is folded back to the upper side (that is, the negative electrode 3 side) in the drawings, but is folded back to the lower side (that is, the positive electrode 2 side) in the drawings. Good. 7 to 9, the first region 681 and the second region 682 on one side in the width direction are shown, but the first region 681 and the second region 682 on the other side in the width direction also have the same structure. May have.
　図７に示す例では、折り返し線６９３は、外周領域６８において、第１領域６８１の幅方向の略中央に位置する。したがって、折り返し部６９５のエッジ（すなわち、折り返し線６９３とは反対側の側縁）は、非折り返し部６９４における第１領域６８１と第２領域６８２との境界と、幅方向の略同じ位置に位置する。換言すれば、第１領域６８１は折り返し線６９３にて２つ折りにされ、第１領域６８１の折り返し部６９５は、第１領域６８１の残りの部位と上下方向に対向する。また、第１領域６８１の折り返し部６９５は、第２領域６８２とは上下方向に対向しない。第２領域６８２は、折り返し線６９３と被覆領域６７との間に位置しているため、折り返されない。換言すれば、折り返し部６９５は第２領域６８２を含まない。 In the example shown in FIG. 7, the folding line 693 is located in the outer peripheral region 68 at substantially the center of the first region 681 in the width direction. Therefore, the edge of the folded-back portion 695 (that is, the side edge opposite to the folded-back line 693) is located at substantially the same position in the width direction as the boundary between the first region 681 and the second region 682 in the non-folded-back portion 694. To do. In other words, the first region 681 is folded in half along the folding line 693, and the folded-back portion 695 of the first region 681 vertically faces the remaining portion of the first region 681. Further, the folded portion 695 of the first region 681 does not face the second region 682 in the vertical direction. The second region 682 is located between the folding line 693 and the covering region 67, and thus is not folded back. In other words, the folded portion 695 does not include the second region 682.
　図８に示す例では、折り返し線６９３は、外周領域６８において、第１領域６８１の幅方向の中央に対して第２領域６８２の反対側（すなわち、当該中央よりも幅方向外側）に位置する。したがって、折り返し部６９５のエッジは、非折り返し部６９４における第１領域６８１と第２領域６８２との境界よりも、幅方向外側（すなわち、被覆領域６７から遠い側）に位置する。換言すれば、第１領域６８１は折り返し線６９３にて２つ折りにされ、第１領域６８１の折り返し部６９５は、第１領域６８１の残りの部位と上下方向に対向する。また、第１領域６８１の折り返し部６９５は、第２領域６８２とは上下方向に対向しない。第２領域６８２は、折り返し線６９３と被覆領域６７との間に位置しているため、折り返されない。換言すれば、折り返し部６９５は第２領域６８２を含まない。 In the example illustrated in FIG. 8, the folding line 693 is located in the outer peripheral region 68 on the opposite side of the second region 682 with respect to the center of the first region 681 in the width direction (that is, outside the center in the width direction). .. Therefore, the edge of the folded portion 695 is located on the outer side in the width direction (that is, the side farther from the covering region 67) than the boundary between the first region 681 and the second region 682 in the non-folded portion 694. In other words, the first region 681 is folded in half along the folding line 693, and the folded-back portion 695 of the first region 681 vertically faces the remaining portion of the first region 681. Further, the folded portion 695 of the first region 681 does not face the second region 682 in the vertical direction. The second region 682 is located between the folding line 693 and the covering region 67, and thus is not folded back. In other words, the folded portion 695 does not include the second region 682.
　図９に示す例では、折り返し線６９３は、外周領域６８において、第１領域６８１の幅方向の中央と第２領域６８２との間に位置する。したがって、折り返し部６９５のエッジは、非折り返し部６９４における第１領域６８１と第２領域６８２との境界よりも、幅方向内側（すなわち、被覆領域６７に近い側）に位置する。換言すれば、第１領域６８１は折り返し線６９３にて２つ折りにされ、第１領域６８１の折り返し部６９５は、第１領域６８１の残りの部位および第２領域６８２と上下方向に対向する。図９に示す例では、折り返し部６９５は、非折り返し部６９４の略全体と上下方向に対向する。第２領域６８２は、折り返し線６９３と被覆領域６７との間に位置しているため、折り返されない。換言すれば、折り返し部６９５は第２領域６８２を含まない。 In the example shown in FIG. 9, the fold line 693 is located in the outer peripheral region 68 between the widthwise center of the first region 681 and the second region 682. Therefore, the edge of the folded portion 695 is located on the inner side in the width direction (that is, on the side closer to the covered region 67) than the boundary between the first region 681 and the second region 682 in the non-folded portion 694. In other words, the first region 681 is folded in two along the folding line 693, and the folded portion 695 of the first region 681 vertically faces the remaining portion of the first region 681 and the second region 682. In the example shown in FIG. 9, the folded portion 695 opposes substantially the entire non-folded portion 694 in the vertical direction. The second region 682 is located between the folding line 693 and the covering region 67, and thus is not folded back. In other words, the folded portion 695 does not include the second region 682.
　次に、図１０Ａおよび図１０Ｂを参照しつつ、リチウム二次電池１の製造の流れの一例について説明する。まず、外装体６の第１シート部６５および第２シート部６６として、２枚のアルミラミネートフィルム（昭和電工パッケージング製、厚さ６１μｍ、ポリプロピレンフィルム／アルミニウム箔／ナイロンフィルムの３層構造）が用意される。また、正極活物質板２２が用意される。正極活物質板２２は、ＬｉＣｏＯ２グリーンシートを焼結することにより形成される。図１０Ａに示す例では、正極活物質板２２は複数の活物質板要素２４を有する。なお、正極活物質板２２が一繋がりの部材（すなわち、一枚板）である場合も、下記の製造方法は略同じである。 Next, an example of the flow of manufacturing the lithium secondary battery 1 will be described with reference to FIGS. 10A and 10B. First, as the first sheet portion 65 and the second sheet portion 66 of the exterior body 6, two aluminum laminated films (manufactured by Showa Denko Packaging, thickness 61 μm, three-layer structure of polypropylene film/aluminum foil/nylon film) Be prepared. Further, the positive electrode active material plate 22 is prepared. The positive electrode active material plate 22 is formed by sintering a LiCoO 2 green sheet. In the example shown in FIG. 10A, the positive electrode active material plate 22 has a plurality of active material plate elements 24. Even when the positive electrode active material plate 22 is a continuous member (that is, a single plate), the following manufacturing method is substantially the same.
　ＬｉＣｏＯ２グリーンシートは、次のようにして作製される。まず、Ｌｉ／Ｃｏのモル比が１．０１となるように秤量されたＣｏ３Ｏ４粉末（正同化学工業株式会社製）とＬｉ２ＣＯ３粉末（本荘ケミカル株式会社製）とが混合された後、７８０℃で５時間保持される。続いて、得られた粉末が、ポットミルにて体積基準Ｄ５０が０．４μｍとなるように粉砕および解砕され、ＬｉＣｏＯ２板状粒子からなる粉末が得られる。 The LiCoO 2 green sheet is manufactured as follows. First, Co 3 O 4 powder (manufactured by Shodo Chemical Industry Co., Ltd.) and Li 2 CO 3 powder (manufactured by Honjo Chemical Co., Ltd.), which were weighed so that the molar ratio of Li/Co was 1.01, were mixed. After that, it is held at 780° C. for 5 hours. Subsequently, the obtained powder is crushed and crushed in a pot mill so that the volume-based D50 is 0.4 μm, and a powder composed of LiCoO 2 plate-like particles is obtained.
　得られたＬｉＣｏＯ２粉末１００重量部と、分散媒（トルエン：イソプロパノール＝１：１）１００重量部と、バインダー（ポリビニルブチラール：品番ＢＭ－２、積水化学工業株式会社製）１０重量部と、可塑剤（ＤＯＰ：Ｄｉ（２－ｅｔｈｙｌｈｅｘｙｌ）ｐｈｔｈａｌａｔｅ、黒金化成株式会社製）４重量部と、分散剤（製品名レオドールＳＰ－Ｏ３０、花王株式会社製）２重量部とが混合される。得られた混合物は、減圧下で撹拌されて脱泡されるとともに、粘度を４０００ｃＰに調整されることによって、ＬｉＣｏＯ２スラリーが調製される。粘度は、ブルックフィールド社製ＬＶＴ型粘度計により測定される。こうして調製されたスラリーが、ポリエチレンテレフタレート（ＰＥＴ）フィルム上にドクターブレード法にてシート状に成形されることにより、ＬｉＣｏＯ２グリーンシートが形成される。乾燥後のＬｉＣｏＯ２グリーンシートの厚さは９８μｍであった。 100 parts by weight of the obtained LiCoO 2 powder, 100 parts by weight of a dispersion medium (toluene:isopropanol=1:1), 10 parts by weight of a binder (polyvinyl butyral: product number BM-2, manufactured by Sekisui Chemical Co., Ltd.), plastic 4 parts by weight of the agent (DOP: Di(2-ethylhexyl) phthalate, manufactured by Kurogane Kasei Co., Ltd.) and 2 parts by weight of the dispersant (product name: Leodol SP-O30, manufactured by Kao Corporation) are mixed. The obtained mixture is stirred under reduced pressure for defoaming, and the viscosity is adjusted to 4000 cP to prepare a LiCoO 2 slurry. The viscosity is measured by a Brookfield LVT viscometer. The slurry thus prepared is formed into a sheet on a polyethylene terephthalate (PET) film by a doctor blade method to form a LiCoO 2 green sheet. The thickness of the LiCoO 2 green sheet after drying was 98 μm.
　次に、ＰＥＴフィルムから剥がされたＬｉＣｏＯ２グリーンシートが、カッターにより５０ｍｍ角に切り出され、下部セッターとしてのマグネシア製セッター（寸法９０ｍｍ角、高さ１ｍｍ）の中央に載置される。また、ＬｉＣｏＯ２シートの上には、上部セッターとしての多孔質マグネシア製セッターが載置される。ＬｉＣｏＯ２シートは、セッターで挟まれた状態で、１２０ｍｍ角のアルミナ鞘（株式会社ニッカトー製）内に載置される。このとき、アルミナ鞘を密閉することなく、０．５ｍｍの隙間を空けて蓋がされる。得られた積層物は、昇温速度２００℃／ｈで６００℃まで昇温されて３時間脱脂された後に、８７０℃まで２００℃／ｈで昇温されて２０時間保持されることで焼成される。焼成後、室温まで降温させた後に焼成体がアルミナ鞘より取り出される。こうして厚さ９０μｍのＬｉＣｏＯ２焼結体板が得られる。得られたＬｉＣｏＯ２焼結体板は、レーザー加工機で１０．５ｍｍ×９．５ｍｍ角の矩形状に切断されて、複数の活物質板要素２４（すなわち、正極活物質板２２）が得られる。 Next, the LiCoO 2 green sheet peeled from the PET film is cut into 50 mm square with a cutter, and placed on the center of a magnesia setter (size 90 mm square, height 1 mm) as a lower setter. Further, a porous magnesia setter as an upper setter is placed on the LiCoO 2 sheet. The LiCoO 2 sheet is placed in a 120 mm square alumina sheath (manufactured by Nikkato Co., Ltd.) while being sandwiched between setters. At this time, the lid is opened with a gap of 0.5 mm without sealing the alumina sheath. The obtained laminate is heated to 600° C. at a heating rate of 200° C./h and degreased for 3 hours, and then heated to 870° C. at 200° C./h and held for 20 hours to be fired. It After firing, the temperature is lowered to room temperature, and then the fired body is taken out from the alumina sheath. In this way, a LiCoO 2 sintered body plate having a thickness of 90 μm is obtained. The obtained LiCoO 2 sintered body plate is cut into a rectangular shape of 10.5 mm×9.5 mm square by a laser processing machine to obtain a plurality of active material plate elements 24 (that is, the positive electrode active material plate 22). ..
　正極活物質板２２が用意されると、ポリアミドイミド（ＰＡＩ）をＮ－メチルピロリドンに溶解させた溶液にアセチレンブラックが混合されてスラリーが調製され、当該スラリー２μＬ（マイクロリットル）が、正極集電体２１（厚さ９ｍｍのアルミニウム箔）上に滴下されて導電性接合層２３が形成される。続いて、導電性接合層２３上に正極活物質板２２が載せられて乾燥される。図１０Ａに示す例では、複数の活物質板要素２４を有する正極活物質板２２が、導電性接合層２３を介して正極集電体２１に接合される。その後、正極集電体２１および正極活物質板２２（すなわち、複数の活物質板要素２４）の複合体が、第１シート部６５上に積層され、正極接合層６３を介して第１シート部６５に接合されることにより、正極組立品２０が形成される。なお、正極集電体２１には、１つの端子７の一方の端部が溶接により予め固定されている。 When the positive electrode active material plate 22 is prepared, acetylene black is mixed with a solution in which polyamideimide (PAI) is dissolved in N-methylpyrrolidone to prepare a slurry, and 2 μL (microliter) of the slurry is used as a positive electrode current collector. The conductive bonding layer 23 is formed by being dropped on the body 21 (aluminum foil having a thickness of 9 mm). Then, the positive electrode active material plate 22 is placed on the conductive bonding layer 23 and dried. In the example shown in FIG. 10A, the positive electrode active material plate 22 having the plurality of active material plate elements 24 is bonded to the positive electrode current collector 21 via the conductive bonding layer 23. Then, the composite body of the positive electrode current collector 21 and the positive electrode active material plate 22 (that is, the plurality of active material plate elements 24) is laminated on the first sheet portion 65, and the first sheet portion is interposed via the positive electrode bonding layer 63. The positive electrode assembly 20 is formed by being bonded to 65. One end of one terminal 7 is fixed to the positive electrode current collector 21 in advance by welding.
　一方、負極集電体３１（厚さ１０μｍの銅箔）上には、負極活物質層３２（厚さ１３０μｍのカーボン層）が塗工される。負極活物質層３２は、活物質としてのグラファイトと、バインダとしてのＰＶＤＦとの混合物を含むカーボン塗工膜である。続いて、負極集電体３１および負極活物質層３２の複合体が、第２シート部６６上に積層され、負極接合層６４を介して第２シート部６６に接合されることにより、負極組立品３０が形成される。なお、負極集電体３１には、１つの端子７の一方の端部が溶接により予め固定されている。 On the other hand, the negative electrode active material layer 32 (carbon layer having a thickness of 130 μm) is coated on the negative electrode current collector 31 (copper foil having a thickness of 10 μm). The negative electrode active material layer 32 is a carbon coating film containing a mixture of graphite as an active material and PVDF as a binder. Subsequently, the composite body of the negative electrode current collector 31 and the negative electrode active material layer 32 is laminated on the second sheet portion 66 and bonded to the second sheet portion 66 via the negative electrode bonding layer 64, whereby the negative electrode assembly is formed. A product 30 is formed. Note that one end of one terminal 7 is fixed to the negative electrode current collector 31 in advance by welding.
　セパレータ４としては、多孔質ポリイミド膜（東京応化工業製　ＴＯＫＳ－８０２３ｉ２）が用意される。そして、正極組立品２０、セパレータ４および負極組立品３０が、正極活物質板２２および負極活物質層３２がセパレータ４と対向するように順に積層され、中間積層体１０が形成される。中間積層体１０では、上下両面が外装体６（すなわち、第１シート部６５および第２シート部６６）により覆われており、正極組立品２０、セパレータ４および負極組立品３０の周囲に第１シート部６５および第２シート部６６が延在している。また、正極組立品２０、セパレータ４および負極組立品３０（以下、まとめて「電池要素」とも呼ぶ。）の上下方向の厚さは０．３３ｍｍである。平面視における電池要素の形状は、２．３ｃｍ×３．２ｃｍの略矩形である。 As the separator 4, a porous polyimide film (TOKS-8023i2 manufactured by Tokyo Ohka Kogyo) is prepared. Then, the positive electrode assembly 20, the separator 4, and the negative electrode assembly 30 are sequentially laminated so that the positive electrode active material plate 22 and the negative electrode active material layer 32 face the separator 4, and the intermediate laminate 10 is formed. In the intermediate laminate 10, both upper and lower surfaces are covered with the exterior body 6 (that is, the first sheet portion 65 and the second sheet portion 66), and the first positive electrode assembly 20, the separator 4, and the negative electrode assembly 30 are surrounded by a first The seat portion 65 and the second seat portion 66 extend. In addition, the thickness of the positive electrode assembly 20, the separator 4, and the negative electrode assembly 30 (hereinafter collectively referred to as “battery element”) in the vertical direction is 0.33 mm. The shape of the battery element in plan view is a substantially rectangular shape of 2.3 cm×3.2 cm.
　続いて、略矩形状の中間積層体１０の４つの辺のうち３つの辺が、熱融着接合により封止される。図１０Ａに示す例では、図中の上側の１つの辺を除く３つの辺が封止される。当該３つの辺には、２つの端子７が突出する１つの辺が含まれている。当該３つの辺の封止では、封止幅が２ｍｍになるように調整された当て冶具が用いられ、中間積層体１０の外周部分が、２００℃、１．５ＭＰａ（メガパスカル）で１０秒間加熱および加圧される。これにより、外装体６の上記外周領域６８（図６参照）のうち、一対の第２領域６８２、および、未封止の辺に対応する一方の第１領域６８１を除く領域において、第１シート部６５と第２シート部６６とが熱融着する。 Subsequently, three of the four sides of the substantially rectangular intermediate laminate 10 are sealed by heat fusion bonding. In the example shown in FIG. 10A, three sides are sealed except one side on the upper side in the figure. The three sides include one side from which the two terminals 7 project. In the sealing of the three sides, a patch jig adjusted to have a sealing width of 2 mm is used, and the outer peripheral portion of the intermediate laminate 10 is heated at 200° C. and 1.5 MPa (megapascal) for 10 seconds. And pressurized. As a result, in the outer peripheral region 68 (see FIG. 6) of the exterior body 6, in the region excluding the pair of second regions 682 and the one first region 681 corresponding to the unsealed side, the first sheet The portion 65 and the second sheet portion 66 are heat-sealed.
　当該３つの辺の封止後、中間積層体１０は、真空乾燥器８１に収容され、水分の除去および接着剤（すなわち、正極接合層６３、負極接合層６４および導電性接合層２３）の乾燥が行われる。このとき、図中の下側に位置する封止された１つの辺において、第２領域６８２の間に存在していたガスが除去される。これにより、当該第２領域６８２において、第１シート部６５および第２シート部６６が、非接触状態にて接触、または、僅かな空隙を挟んで近接する。 After sealing the three sides, the intermediate laminate 10 is housed in the vacuum dryer 81 to remove moisture and dry the adhesive (that is, the positive electrode bonding layer 63, the negative electrode bonding layer 64, and the conductive bonding layer 23). Is done. At this time, the gas existing between the second regions 682 is removed on one sealed side located on the lower side in the drawing. As a result, in the second region 682, the first sheet portion 65 and the second sheet portion 66 are in contact with each other in the non-contact state, or are close to each other with a slight gap therebetween.
　次に、図１０Ｂに示されるように、中間積層体１０がグローブボックス８２内に収容される。そして、中間積層体１０の未封止の１つの辺において、第１シート部６５および第２シート部６６の間に注入器具８３が挿入され、注入器具８３を介して電解液５が中間積層体１０内に注入される。電解液５は、ＥＣおよびＧＢＬを体積比１：３で含む混合溶媒に、ＬｉＢＦ４を１．５ｍｏｌ／Ｌの濃度となるように溶解させ、さらに、ＶＣを添加剤として５重量％の濃度となるように添加した液体である。 Next, as shown in FIG. 10B, the intermediate laminate 10 is housed in the glove box 82. Then, on one unsealed side of the intermediate laminated body 10, the injection device 83 is inserted between the first sheet portion 65 and the second sheet portion 66, and the electrolytic solution 5 receives the electrolytic solution 5 via the injection device 83. Injected into 10. The electrolyte solution 5 was prepared by dissolving LiBF 4 in a mixed solvent containing EC and GBL in a volume ratio of 1:3 so as to have a concentration of 1.5 mol/L, and further adding 5% by weight of VC as an additive. It is a liquid added so that.
　電解液５の注入が終了すると、グローブボックス８２内の絶対圧５ｋＰａの減圧雰囲気下において、上記未封止の１つの辺が、簡易シーラにより仮封止（すなわち、減圧封止）される。続いて、中間積層体１０に対して初期充電が施され、７日間のエージングが行われる。エージングが終了すると、第１シート部６５および第２シート部６６のうち、仮封止された１つの辺の外縁近傍の部位（すなわち、電池要素を含まない末端部分）が切除され、エージングにより発生した水分等を含むガスが除去される（すなわち、ガス抜きが行われる）。 When the injection of the electrolytic solution 5 is completed, the unsealed one side is temporarily sealed (that is, vacuum-sealed) in the glove box 82 under a depressurized atmosphere with an absolute pressure of 5 kPa. Then, the intermediate laminate 10 is subjected to initial charging and aging for 7 days. When the aging ends, a portion of the first sheet portion 65 and the second sheet portion 66 near the outer edge of one temporarily sealed side (that is, the end portion that does not include the battery element) is cut off and generated by the aging. The gas containing the water and the like is removed (that is, degassing is performed).
　ガス抜きが終了すると、グローブボックス８２内の絶対圧５ｋＰａの減圧雰囲気下において、上述の切除により形成された辺の熱融着接合による封止が行われる。当該封止では、上述の３つの辺の封止と同様に、封止幅が２ｍｍになるように調整された当て冶具が用いられ、第１シート部６５および第２シート部６６が、２００℃、１．５ＭＰａで１０秒間加熱および加圧される。これにより、外装体６の上記外周領域６８（図６参照）のうち、図中の上側に位置する１つの辺の第１領域６８１において、第１シート部６５と第２シート部６６とが熱融着され、リチウム二次電池１が形成される。また、図中の上側に位置する当該１つの辺の第２領域６８２において、第１シート部６５および第２シート部６６が、非接触状態にて接触、または、僅かな空隙を挟んで近接する。その後、外装体６の外周部における余分な部位が切除されて、リチウム二次電池１の形状が整えられる。また、図７ないし図９に例示するリチウム二次電池１が製造される場合は、外装体６の折り返し部６９５が折り返し線６９３にて折り返される。リチウム二次電池１の平面視における形状は、３８ｍｍ×２７ｍｍの長方形であり、厚さは０．４５ｍｍ以下であり、容量は３０ｍＡｈであった。 When the degassing is completed, the sides formed by the above cutting are sealed by heat fusion bonding in a depressurized atmosphere in the glove box 82 with an absolute pressure of 5 kPa. In the said sealing, the patch jig adjusted so that the sealing width might be 2 mm was used similarly to the above-mentioned three sides sealing, and the 1st sheet part 65 and the 2nd sheet part 66 are 200 degreeC. , And heated and pressurized at 1.5 MPa for 10 seconds. As a result, in the outer peripheral region 68 (see FIG. 6) of the exterior body 6, in the first region 681 on one side located on the upper side in the drawing, the first sheet portion 65 and the second sheet portion 66 are heated. By fusion bonding, the lithium secondary battery 1 is formed. Further, in the second region 682 of the one side located on the upper side in the drawing, the first sheet portion 65 and the second sheet portion 66 are in contact with each other in a non-contact state, or are close to each other with a slight gap therebetween. .. After that, an extra portion of the outer peripheral portion of the outer package 6 is cut off, and the shape of the lithium secondary battery 1 is adjusted. When the lithium secondary battery 1 illustrated in FIGS. 7 to 9 is manufactured, the folded-back portion 695 of the outer package 6 is folded back along the folded-back line 693. The shape of the lithium secondary battery 1 in plan view was a rectangle of 38 mm×27 mm, the thickness was 0.45 mm or less, and the capacity was 30 mAh.
　上述の製造方法により製造されたリチウム二次電池１では、正極活物質板２２（すなわち、ＬｉＣｏＯ２焼結体板）における一次粒子の平均配向角度は、１６°であった。当該平均配向角度は、次のようにして測定した。まず、上記ＬｉＣｏＯ２焼結体板をクロスセクションポリッシャ（ＣＰ）（日本電子株式会社製、ＩＢ－１５０００ＣＰ）により研磨し、得られた断面（すなわち、ＬｉＣｏＯ２焼結体板の主面に垂直な断面）を１０００倍の視野（１２５μｍ×１２５μｍ）でＥＢＳＤ測定して、ＥＢＳＤ像を得た。このＥＢＳＤ測定は、ショットキー電界放出形走査電子顕微鏡（日本電子株式会社製、型式ＪＳＭ－７８００Ｆ）を用いて行った。そして、得られたＥＢＳＤ像において特定される全ての粒子について、一次粒子の（００３）面とＬｉＣｏＯ２焼結体板の主面とがなす角度（すなわち、（００３）からの結晶方位の傾き）を傾斜角として求め、それらの角度の平均値を一次粒子の平均配向角度とした。 In the lithium secondary battery 1 manufactured by the manufacturing method described above, the average orientation angle of the primary particles in the positive electrode active material plate 22 (that is, the LiCoO 2 sintered body plate) was 16°. The average orientation angle was measured as follows. First, the above-mentioned LiCoO 2 sintered body plate was polished by a cross section polisher (CP) (IB-15000CP manufactured by JEOL Ltd.) to obtain a cross section (that is, perpendicular to the main surface of the LiCoO 2 sintered body plate). The cross section was subjected to EBSD measurement in a field of view (125 μm×125 μm) of 1000 times to obtain an EBSD image. This EBSD measurement was performed using a Schottky field emission scanning electron microscope (JSM-7800F, manufactured by JEOL Ltd.). Then, for all the particles specified in the obtained EBSD image, the angle formed by the (003) plane of the primary particles and the main surface of the LiCoO 2 sintered body plate (that is, the inclination of the crystal orientation from (003)) Was determined as the tilt angle, and the average value of these angles was defined as the average orientation angle of the primary particles.
　ＬｉＣｏＯ２焼結体板の板厚は、上述のように９０μｍであった。当該板厚は、ＬｉＣｏＯ２焼結体板をクロスセクションポリッシャ（ＣＰ）（日本電子株式会社製、ＩＢ－１５０００ＣＰ）により研磨し、得られた断面をＳＥＭ観察（日本電子製、ＪＳＭ６３９０ＬＡ）して測定した。なお、上述の乾燥後のＬｉＣｏＯ２グリーンシートの厚さも、同様にして測定されたものである。 The plate thickness of the LiCoO 2 sintered body plate was 90 μm as described above. The plate thickness is measured by polishing a LiCoO 2 sintered plate with a cross section polisher (CP) (manufactured by JEOL Ltd., IB-15000CP), and observing the obtained cross section by SEM (JSM6390LA, JEOL Ltd.). did. The thickness of the LiCoO 2 green sheet after the above-mentioned drying was also measured in the same manner.
　ＬｉＣｏＯ２焼結体板の気孔率は、３０％であった。当該気孔率は、次のようにして測定した。ＬｉＣｏＯ２焼結体板をクロスセクションポリッシャ（ＣＰ）（日本電子株式会社製、ＩＢ－１５０００ＣＰ）により研磨し、得られた断面を１０００倍の視野（１２５μｍ×１２５μｍ）でＳＥＭ観察（日本電子製、ＪＳＭ６３９０ＬＡ）した。得られたＳＥＭ像を画像解析し、全ての気孔の面積をＬｉＣｏＯ２焼結体板の面積で除算し、得られた値に１００を乗じることにより気孔率（％）を算出した。 The porosity of the LiCoO 2 sintered body plate was 30%. The porosity was measured as follows. The LiCoO 2 sintered body plate was polished by a cross section polisher (CP) (manufactured by JEOL Ltd., IB-15000CP), and the obtained cross section was observed with an SEM under a field of view of 1000 times (125 μm×125 μm). JSM6390LA). The obtained SEM image was subjected to image analysis, the area of all the pores was divided by the area of the LiCoO 2 sintered body plate, and the obtained value was multiplied by 100 to calculate the porosity (%).
　ＬｉＣｏＯ２焼結体板の平均気孔径は、０．８μｍであった。当該平均気孔径は、水銀ポロシメーター（島津製作所製、オートポアＩＶ９５１０）を用いて、水銀圧入法により測定した。 The average pore diameter of the LiCoO 2 sintered body plate was 0.8 μm. The average pore diameter was measured by a mercury porosimetry using a mercury porosimeter (manufactured by Shimadzu Corporation, Autopore IV9510).
　上述のように、リチウム二次電池１がスマートカードに搭載される際には、リチウム二次電池１をカード基材で挟み込んで常温にて加圧するコールドラミネート、または、リチウム二次電池１をカード基材で挟み込んで加熱および加圧するホットラミネートが行われる。このように、対象デバイスの製造の際に、リチウム二次電池１に対して上下方向の圧力が加えられると、被覆領域６７が上下方向に圧縮され、被覆領域６７において第１シート部６５と第２シート部６６との間に存在する電解液５の一部が、被覆領域６７の周囲に向かって押し出される。 As described above, when the lithium secondary battery 1 is mounted on a smart card, the lithium secondary battery 1 is sandwiched between card base materials and cold laminated to press at room temperature, or the lithium secondary battery 1 is used as a card. Hot laminating is performed in which the substrate is sandwiched and heated and pressed. As described above, when the vertical pressure is applied to the lithium secondary battery 1 during the manufacture of the target device, the covering region 67 is compressed in the vertical direction, and the first sheet portion 65 and the first sheet portion 65 are compressed in the covering region 67. A part of the electrolytic solution 5 existing between the second sheet portion 66 and the second sheet portion 66 is extruded toward the periphery of the covering region 67.
　被覆領域６７から押し出された電解液５は、第２領域６８２において非接合状態で接触または近接する第１シート部６５および第２シート部６６の間に流入し、図１１に示すように、第１シート部６５と第２シート部６６とを上下方向に離間させる。そして、当該電解液５は、第２領域６８２において第１シート部６５と第２シート部６６との間にできた空間に保持される。 The electrolytic solution 5 extruded from the covering region 67 flows between the first sheet portion 65 and the second sheet portion 66 which are in contact with or close to each other in the second region 682 in a non-bonded state, and as shown in FIG. The first sheet portion 65 and the second sheet portion 66 are vertically separated from each other. Then, the electrolytic solution 5 is held in the space formed between the first sheet portion 65 and the second sheet portion 66 in the second region 682.
　このため、電解液５が、第１領域６８１において接合されている第１シート部６５と第２シート部６６との間に浸入して第１シート部６５と第２シート部６６とを剥離させることを防止または抑制することができる。その結果、外装体６の封止性能の低下、および、第１シート部６５と第２シート部６６との間からの電解液５の漏出を防止または抑制することができる。なお、リチウム二次電池１に加えられている圧力が除かれると、第２領域６８２へと拡散していた電解液５の大部分は、毛細管現象等により被覆領域６７へと戻る。上述の折り返し線６９３にて外周領域６８が折り返されるリチウム二次電池１（図７ないし図９参照）においても同様である。 Therefore, the electrolytic solution 5 penetrates between the first sheet portion 65 and the second sheet portion 66 joined in the first region 681 to separate the first sheet portion 65 and the second sheet portion 66 from each other. This can be prevented or suppressed. As a result, it is possible to prevent or suppress deterioration of the sealing performance of the outer package 6 and leakage of the electrolytic solution 5 from between the first sheet portion 65 and the second sheet portion 66. When the pressure applied to the lithium secondary battery 1 is removed, most of the electrolytic solution 5 that has diffused into the second region 682 returns to the coating region 67 due to a capillary phenomenon or the like. The same applies to the lithium secondary battery 1 (see FIGS. 7 to 9) in which the outer peripheral region 68 is folded back along the folding line 693 described above.
　一方、外装体６の被覆領域６７と第１領域６８１との間に第２領域６８２が設けられていない場合、または、第２領域６８２の幅が過剰に小さい場合、被覆領域６７から押し出された電解液５は、第１領域６８１において接合されている第１シート部６５と第２シート部６６との間に浸入し、第１シート部６５と第２シート部６６とを剥離させる可能性がある。さらには、剥離された第１シート部６５と第２シート部６６との間から、電解液５がリチウム二次電池１の外部に漏出する可能性もある。特に、リチウム二次電池１がホットラミネートによりスマートカード等に搭載される場合、電解液５の熱膨張等も生じるため、被覆領域６７から押し出される電解液５の体積が増大する傾向がある。このため、外装体６の封止性能の低下、および、電解液のリチウム二次電池１外部への漏出が生じる可能性が増大する。 On the other hand, when the second region 682 is not provided between the covering region 67 and the first region 681 of the exterior body 6, or when the width of the second region 682 is excessively small, it is extruded from the covering region 67. The electrolytic solution 5 may infiltrate between the first sheet portion 65 and the second sheet portion 66 joined in the first region 681, and may cause the first sheet portion 65 and the second sheet portion 66 to be separated from each other. is there. Further, the electrolytic solution 5 may leak to the outside of the lithium secondary battery 1 from between the peeled first sheet portion 65 and the second sheet portion 66. In particular, when the lithium secondary battery 1 is mounted on a smart card or the like by hot lamination, thermal expansion of the electrolytic solution 5 also occurs, so that the volume of the electrolytic solution 5 extruded from the covering region 67 tends to increase. Therefore, the sealing performance of the outer package 6 is deteriorated, and the possibility that the electrolytic solution leaks to the outside of the lithium secondary battery 1 increases.
　また、第２領域６８２の幅が過剰に大きい場合、リチウム二次電池１全体の大きさはある程度制限されるため、正極活物質板２２および負極活物質層３２の面積が小さくなり、電池特性が低下する可能性がある。具体的には、リチウム二次電池１のレート特性およびサイクル特性が低下する可能性がある。 Further, when the width of the second region 682 is excessively large, the size of the entire lithium secondary battery 1 is limited to some extent, so that the areas of the positive electrode active material plate 22 and the negative electrode active material layer 32 are reduced, and the battery characteristics are reduced. It may decrease. Specifically, the rate characteristics and cycle characteristics of the lithium secondary battery 1 may deteriorate.
　次に、表１を参照しつつ、第２領域６８２の幅とリチウム二次電池１の電池特性（すなわち、レート特性およびサイクル特性）との関係について説明する。 Next, referring to Table 1, the relationship between the width of the second region 682 and the battery characteristics (that is, rate characteristics and cycle characteristics) of the lithium secondary battery 1 will be described.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表中のＡ１／Ｂ３は、上述の第２領域幅Ａ１を活物質領域幅Ｂ３により除算した値である。換言すれば、Ａ１／Ｂ３は、活物質領域幅Ｂ３に対する第２領域幅Ａ１の割合である。比較例１～３、実施例１～６および比較例４では、Ａ１／Ｂ３が変更されている。なお、比較例１～３、実施例１～６および比較例４では、第１領域６８１の幅は２ｍｍである。 A1/B3 in the table is a value obtained by dividing the above-mentioned second area width A1 by the active material area width B3. In other words, A1/B3 is the ratio of the second region width A1 to the active material region width B3. In Comparative Examples 1 to 3, Examples 1 to 6 and Comparative Example 4, A1/B3 is changed. In Comparative Examples 1 to 3, Examples 1 to 6 and Comparative Example 4, the width of the first region 681 is 2 mm.
　表中の液漏れは、リチウム二次電池１に上述のホットラミネートと略同様の加工を施した場合の電解液５の漏出の有無を示す。具体的には、１３５℃に加熱した熱板プレスにより、加工圧力３ＭＰａにてリチウム二次電池１を上下方向に加圧し、リチウム二次電池１の外部に電解液５が漏出しているか否かを目視で確認した。 The liquid leakage in the table indicates the presence or absence of leakage of the electrolytic solution 5 when the lithium secondary battery 1 is subjected to substantially the same processing as the above hot lamination. Specifically, the hot plate press heated to 135° C. vertically pressurizes the lithium secondary battery 1 at a processing pressure of 3 MPa to determine whether the electrolytic solution 5 leaks to the outside of the lithium secondary battery 1. Was visually confirmed.
　表中のレート特性は、後述する第１容量により第２容量を除算して得た溶量比（％）である。第１容量は、リチウム二次電池１を０．２Ｃで４．２Ｖまで充電した後、０．２Ｃで３．０Ｖまで放電して算出した容量である。第２容量は、リチウム二次電池１を０．２Ｃで４．２Ｖまで充電した後、１．０Ｃで３．０Ｖまで放電して算出した容量である。表中のサイクル特性は、リチウム二次電池１を０．５Ｃで４．２Ｖまで充電して０．５Ｃで３．０Ｖまで放電する工程を３００回繰り返し、繰り返し後のリチウム二次電池１の容量を、繰り返し前のリチウム二次電池１の容量で除算して求めた値（％）である。 The rate characteristics in the table are the dissolution ratio (%) obtained by dividing the second capacity by the first capacity described later. The first capacity is a capacity calculated by charging the lithium secondary battery 1 at 0.2C to 4.2V and then discharging at 0.2C to 3.0V. The second capacity is a capacity calculated by charging the lithium secondary battery 1 at 0.2C to 4.2V and then discharging at 1.0C to 3.0V. The cycle characteristics in the table indicate that the lithium secondary battery 1 is charged up to 4.2 V at 0.5 C and discharged up to 3.0 V at 0.5 C, repeated 300 times, and the capacity of the lithium secondary battery 1 after the repetition is repeated. Is a value (%) obtained by dividing by the capacity of the lithium secondary battery 1 before repetition.
　比較例１～３では、Ａ１／Ｂ３は、０．００６７未満である。実施例１～６では、Ａ１／Ｂ３は、０．０２～１．０である。比較例４では、Ａ１／Ｂ３は、１．２である。比較例１～３では、電解液５の漏出が発生した。一方、実施例１～６および比較例４では、電解液５の漏出は生じなかった。また、比較例１～３および実施例１～６では、レート特性は７０％～７３％であり、サイクル特性は９０％～９４％であった。一方、比較例４では、レート特性は５５％と低く、サイクル特性も４９％と低かった。 In Comparative Examples 1 to 3, A1/B3 is less than 0.0067. In Examples 1 to 6, A1/B3 is 0.02 to 1.0. In Comparative Example 4, A1/B3 is 1.2. In Comparative Examples 1 to 3, leakage of the electrolytic solution 5 occurred. On the other hand, in Examples 1 to 6 and Comparative Example 4, the electrolyte solution 5 did not leak. Further, in Comparative Examples 1 to 3 and Examples 1 to 6, the rate characteristics were 70% to 73% and the cycle characteristics were 90% to 94%. On the other hand, in Comparative Example 4, the rate characteristic was low at 55% and the cycle characteristic was low at 49%.
　以上に説明したように、リチウム二次電池１は、正極２と、セパレータ４と、負極３と、電解液５と、外装体６と、２つの端子７とを備える。セパレータ４は、所定の重ね合わせ方向において、正極２上に配置される。負極３は、当該重ね合わせ方向において、セパレータ４の正極２とは反対側に配置される。電解液５は、正極２、負極３およびセパレータ４に含浸する。外装体６は、重ね合わせ方向の両側から正極２および負極３を被覆する２層のシート部（すなわち、第１シート部６５および第２シート部６６）を有する。外装体６は、正極２、セパレータ４、負極３および電解液５を内部に収容する矩形シート状の部材である。２つの端子７は、外装体６の内部にて正極２および負極３にそれぞれ接続される。２つの端子７は、外装体６の外部へと延びる。 As described above, the lithium secondary battery 1 includes the positive electrode 2, the separator 4, the negative electrode 3, the electrolytic solution 5, the outer casing 6, and the two terminals 7. The separator 4 is arranged on the positive electrode 2 in a predetermined stacking direction. The negative electrode 3 is arranged on the side of the separator 4 opposite to the positive electrode 2 in the stacking direction. The electrolytic solution 5 impregnates the positive electrode 2, the negative electrode 3, and the separator 4. The outer package 6 has a two-layer sheet portion (that is, the first sheet portion 65 and the second sheet portion 66) that covers the positive electrode 2 and the negative electrode 3 from both sides in the stacking direction. The outer package 6 is a rectangular sheet-shaped member that accommodates the positive electrode 2, the separator 4, the negative electrode 3, and the electrolytic solution 5 therein. The two terminals 7 are connected to the positive electrode 2 and the negative electrode 3 inside the exterior body 6, respectively. The two terminals 7 extend to the outside of the exterior body 6.
　外装体６は、被覆領域６７と、外周領域６８とを備える。被覆領域６７は、正極２、セパレータ４および負極３と重ね合わせ方向に重なる矩形状の領域である。外周領域６８は、被覆領域６７の周囲を囲む矩形枠状の領域である。外周領域６８は、第１領域６８１と、第２領域６８２とを備える。第１領域６８１は、２つの端子７が配置される辺以外の一対の辺（すなわち、一対の長辺６９１）に沿ってそれぞれ延びる帯状領域である。第１領域６８１では、上記２層のシート部（すなわち、第１シート部６５および第２シート部６６）が接合される。第２領域６８２は、一対の第１領域６８１のうち少なくとも一方の第１領域６８１と被覆領域６７との間にて、被覆領域６７に沿って延びる帯状領域である。第２領域６８２では、上記２層のシート部（すなわち、第１シート部６５および第２シート部６６）が、非接合状態で接触または近接する。 The outer package 6 includes a covering region 67 and an outer peripheral region 68. The covering region 67 is a rectangular region that overlaps the positive electrode 2, the separator 4, and the negative electrode 3 in the stacking direction. The outer peripheral area 68 is a rectangular frame-shaped area surrounding the periphery of the covered area 67. The outer peripheral area 68 includes a first area 681 and a second area 682. The first region 681 is a strip-shaped region that extends along a pair of sides (that is, a pair of long sides 691) other than the side where the two terminals 7 are arranged. In the first region 681, the two-layer sheet portions (that is, the first sheet portion 65 and the second sheet portion 66) are joined. The second region 682 is a strip-shaped region extending along the covering region 67 between at least one first region 681 of the pair of first regions 681 and the covering region 67. In the second region 682, the two-layer sheet portions (that is, the first sheet portion 65 and the second sheet portion 66) are in contact with or close to each other in a non-bonded state.
　これにより、リチウム二次電池１の電解液５が被覆領域６７から外周領域６８へと押し出された場合に、第２領域６８２において、第１シート部６５および第２シート部６６が離間し、第１シート部６５と第２シート部６６との間の空間に電解液５を保持することができる。したがって、被覆領域６７から押し出された電解液５による第１領域６８１の剥離（すなわち、第１領域６８１における第１シート部６５と第２シート部６６との剥離）を抑制することができる。また、リチウム二次電池１の外部への電解液５の漏出を抑制することができる。 As a result, when the electrolytic solution 5 of the lithium secondary battery 1 is extruded from the covering region 67 to the outer peripheral region 68, the first sheet portion 65 and the second sheet portion 66 are separated from each other in the second region 682, The electrolytic solution 5 can be held in the space between the first sheet portion 65 and the second sheet portion 66. Therefore, peeling of the first region 681 (that is, peeling between the first sheet portion 65 and the second sheet portion 66 in the first region 681) by the electrolytic solution 5 extruded from the covering region 67 can be suppressed. In addition, leakage of the electrolytic solution 5 to the outside of the lithium secondary battery 1 can be suppressed.
　上述のように、被除数である第２領域幅Ａ１を除数である活物質領域幅Ｂ３により除算した値は、０．０２以上かつ１以下であることが好ましい。活物質領域幅Ｂ３は、一対の長辺６９１に垂直な幅方向における正極２の活物質領域の幅である正極活物質幅と、負極３の活物質領域の幅である負極活物質幅とが異なる場合は、正極活物質幅および負極活物質幅のうち小さい方であり、正極活物質幅と負極活物質幅とが同じである場合は、正極活物質幅および負極活物質幅のうちいずれか一方である。第２領域幅Ａ１は、一対の第１領域６８１のうち一方の第１領域６８１と被覆領域６７との間にのみ第２領域６８２が存在する場合は、当該１つの第２領域６８２の幅であり、一対の第１領域６８１の双方と被覆領域６７との間に一対の第２領域６８２が存在する場合は、当該一対の第２領域６８２の合計幅である。これにより、表１中の実施例１～６に示すように、リチウム二次電池１からの電解液５の漏出を防止することができるとともに、電池特性（すなわち、レート特性およびサイクル特性）の低下を防止または抑制することができる。 As described above, the value obtained by dividing the second area width A1 which is the dividend by the active material area width B3 which is the divisor is preferably 0.02 or more and 1 or less. The active material region width B3 is obtained by dividing the positive electrode active material width which is the width of the active material region of the positive electrode 2 and the negative electrode active material width which is the width of the active material region of the negative electrode 3 in the width direction perpendicular to the pair of long sides 691. When different, it is the smaller of the positive electrode active material width and the negative electrode active material width, and when the positive electrode active material width and the negative electrode active material width are the same, either the positive electrode active material width or the negative electrode active material width. On the other hand. The second region width A1 is the width of the one second region 682 when the second region 682 exists only between the one first region 681 and the covering region 67 of the pair of first regions 681. If there is a pair of second regions 682 between both the pair of first regions 681 and the covering region 67, the total width of the pair of second regions 682 is present. As a result, as shown in Examples 1 to 6 in Table 1, leakage of the electrolytic solution 5 from the lithium secondary battery 1 can be prevented and the battery characteristics (that is, rate characteristics and cycle characteristics) deteriorate. Can be prevented or suppressed.
　リチウム二次電池１では、図７ないし図９に示すように、上記少なくとも一方の第１領域６８１は、一対の長辺６９１に平行に延びる折り返し線６９３にて幅方向に折り返されることが好ましい。これにより、リチウム二次電池１の平面視における大きさ（いわゆる、フットプリント）を小型化することができる。その結果、リチウム二次電池１が搭載される対象デバイスを小型化することができる。あるいは、対象デバイスにおけるリチウム二次電池１の搭載スペースを小型化することができる。 In the lithium secondary battery 1, as shown in FIGS. 7 to 9, it is preferable that the at least one first region 681 be folded back in the width direction at a folding line 693 extending parallel to the pair of long sides 691. As a result, the size (so-called footprint) of the lithium secondary battery 1 in plan view can be reduced. As a result, the target device in which the lithium secondary battery 1 is mounted can be downsized. Alternatively, it is possible to reduce the mounting space of the lithium secondary battery 1 in the target device.
　好ましくは、折り返し線６９３は、上記少なくとも一方の第１領域６８１の幅方向の中央、または、当該少なくとも一方の第１領域６８１の幅方向の中央に対して第２領域６８２の反対側に位置する（図７および図８参照）。これにより、折り返し部６９５が第２領域６８２と上下方向に重ならないため、被覆領域６７から押し出された電解液５が第２領域６８２に流入する際に、第２領域６８２の膨張が折り返し部６９５により阻害されることを防止することができる。したがって、第２領域６８２が好適に膨張し、上記電解液５を第２領域６８２において好適に保持することができる。 Preferably, the folding line 693 is located at the center of the at least one first region 681 in the width direction or on the opposite side of the second region 682 with respect to the center of the at least one first region 681 in the width direction. (See Figures 7 and 8). Accordingly, since the folded-back portion 695 does not vertically overlap the second region 682, the expansion of the second region 682 is caused by the expansion of the second region 682 when the electrolytic solution 5 extruded from the covering region 67 flows into the second region 682. Can be prevented. Therefore, the second region 682 is appropriately expanded, and the electrolytic solution 5 can be appropriately retained in the second region 682.
　また、折り返し線６９３は、上記少なくとも一方の第１領域６８１の幅方向の中央と、第２領域６８２との間に位置することも好ましい（図９参照）。これにより、折り返し部６９５が第２領域６８２と上下方向に重なる幅方向内側の位置まで折り返される。その結果、リチウム二次電池１の平面視における大きさ（いわゆる、フットプリント）を、さらに小型化することができる。 It is also preferable that the folding line 693 is located between the center of the at least one first region 681 in the width direction and the second region 682 (see FIG. 9). As a result, the folded-back portion 695 is folded back to a position on the inner side in the width direction that overlaps the second region 682 in the vertical direction. As a result, the size of the lithium secondary battery 1 in plan view (so-called footprint) can be further reduced.
　上述のように、正極２は、導電性を有するシート状の集電体（すなわち、正極集電体２１）と、リチウム複合酸化物を含む板状セラミック焼結体である活物質板（すなわち、正極活物質板２２）とを備えることが好ましい。これにより、リチウム二次電池１の上記電池特性をさらに向上することができる。 As described above, the positive electrode 2 includes the conductive sheet-shaped current collector (that is, the positive electrode current collector 21 ), and the active material plate (that is, the positive electrode current collector 21) that is the plate-shaped ceramic sintered body containing the lithium composite oxide (that is, The positive electrode active material plate 22) is preferably provided. Thereby, the battery characteristics of the lithium secondary battery 1 can be further improved.
　より好ましくは、正極２の正極活物質板２２は、層状岩塩構造を有する複数の一次粒子が結合した構造を有している。また、当該複数の一次粒子の平均傾斜角は、０°よりも大きく、かつ、３０°以下であることが好ましい。当該平均傾斜角は、複数の一次粒子の（００３）面と正極活物質板２２の主面とが成す角度の平均値である。これにより、充放電サイクルに伴う結晶格子の伸縮の際に発生する正極活物質板２２の内部応力が、正極活物質板２２の導電性接合層２３および正極集電体２１と対向する主面に加わることを抑制することができる。 More preferably, the positive electrode active material plate 22 of the positive electrode 2 has a structure in which a plurality of primary particles having a layered rock salt structure are bonded. The average tilt angle of the plurality of primary particles is preferably larger than 0° and 30° or less. The average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the positive electrode active material plate 22. As a result, the internal stress of the positive electrode active material plate 22 generated when the crystal lattice expands and contracts due to the charge/discharge cycle is applied to the conductive bonding layer 23 of the positive electrode active material plate 22 and the main surface facing the positive electrode current collector 21. It is possible to suppress the addition.
　このように、導電性接合層２３に接触する正極活物質板２２の主面を、結晶格子の伸縮の際に発生する内部応力が加わりにくい主面とすることにより、正極活物質板２２と正極集電体２１との接合強度の低下を抑制することができる。その結果、リチウム二次電池１の充電時および放電時における電圧の安定性を向上することができる。 In this way, by making the main surface of the positive electrode active material plate 22 in contact with the conductive bonding layer 23 the main surface to which internal stress generated when the crystal lattice expands or contracts is not easily applied, the positive electrode active material plate 22 and the positive electrode It is possible to suppress a decrease in the bonding strength with the current collector 21. As a result, it is possible to improve the voltage stability during charging and discharging of the lithium secondary battery 1.
　上述のリチウム二次電池１では、薄型であるにもかかわらず、加圧時等におけるリチウム二次電池１の外部への電解液５の漏出を抑制することができる。したがって、リチウム二次電池１は、薄型の比較的変形しやすいデバイス、すなわち、シート状デバイスまたは可撓性を有するデバイス（例えば、スマートカード）における電力供給源に特に適している。 Despite the thinness of the lithium secondary battery 1 described above, leakage of the electrolyte solution 5 to the outside of the lithium secondary battery 1 during pressurization or the like can be suppressed even though it is thin. Therefore, the lithium secondary battery 1 is particularly suitable as a power supply source in a thin and relatively deformable device, that is, a sheet-shaped device or a flexible device (for example, a smart card).
　上述のように、リチウム二次電池１は、電解液５の漏出を抑制することができるため、製造の際に被覆領域６７から電解液５が押し出される工程が施される対象デバイス、すなわち、製造の際に加熱しつつ加圧する工程が施される対象デバイスにおける電力供給源として利用される場合に特に適している。 As described above, since the lithium secondary battery 1 can suppress the leakage of the electrolytic solution 5, it is a target device that is subjected to the step of extruding the electrolytic solution 5 from the covering region 67 during manufacturing, that is, manufacturing. It is particularly suitable when it is used as a power supply source in a target device to which a step of applying pressure while heating is performed.
　上述のリチウム二次電池１では、様々な変更が可能である。 Various changes can be made to the lithium secondary battery 1 described above.
　例えば、第２領域幅Ａ１／活物質領域幅Ｂ３は、０よりも大きければ、０．０２未満であってもよい。あるいは、第２領域幅Ａ１／活物質領域幅Ｂ３は、１よりも大きくてもよい。いずれの場合であっても、リチウム二次電池１の外部への電解液５の漏出を抑制することができる。 For example, the second region width A1/active material region width B3 may be less than 0.02 as long as it is greater than 0. Alternatively, the second area width A1/active material area width B3 may be larger than one. In any case, leakage of the electrolytic solution 5 to the outside of the lithium secondary battery 1 can be suppressed.
　図７ないし図９に示す例では、折り返し線６９３は第１領域６８１上に位置するが、第２領域６８２上に折り返し線６９３が配置されてもよい。この場合、折り返し部６９５の一部（すなわち、幅方向内側の端部）は、被覆領域６７と上下方向に重なっていてもよい。 In the example shown in FIGS. 7 to 9, the folding line 693 is located on the first region 681, but the folding line 693 may be arranged on the second region 682. In this case, a part of the folded-back portion 695 (that is, the end portion on the inner side in the width direction) may overlap the covering region 67 in the vertical direction.
　図７ないし図９に示す例では、折り返し部６９５は折り返し線６９３にて約１８０°折り返されているが、折り返し角度は１８０°未満であってもよい。当該折り返し角度は、図７ないし図９のような断面図において、折り返し前の折り返し部６９５と、折り返し後の折り返し部６９５とが成す角度である。当該折り返し角度は、９０°以上かつ１８０°以下であることが好ましい。 In the example shown in FIGS. 7 to 9, the folded-back portion 695 is folded back by about 180° at the folded-back line 693, but the folded-back angle may be less than 180°. The folding-back angle is an angle formed by the folding-back portion 695 before folding and the folding-back portion 695 after folding in the cross-sectional views as shown in FIGS. 7 to 9. The folding angle is preferably 90° or more and 180° or less.
　また、図７ないし図９に示す例では、折り返し部６９５は折り返し線６９３にて１回のみ折り返されているが、折り返し回数は複数であってもよい。例えば、第１領域６８１の幅方向外側の部位が、幅方向内側へと複数回折り返され、断面が渦巻き状の折り返し部６９５が形成されてもよい。 Further, in the example shown in FIGS. 7 to 9, the folding part 695 is folded only once at the folding line 693, but the number of folding may be plural. For example, a portion on the outer side in the width direction of the first region 681 may be folded back multiple times inward in the width direction to form a folded portion 695 having a spiral cross section.
　外装体６の第１シート部６５および第２シート部６６が非接合状態で接触または近接する第２領域６８２は、上述のように、外装体６において２つの端子７が設けられる短辺に隣接する長辺６９１に沿って設けられるが、長辺６９１以外の辺（すなわち、２つの端子７が設けられる短辺と平行なもう１つの短辺）に沿って設けられてもよい。 As described above, the second region 682 where the first sheet portion 65 and the second sheet portion 66 of the exterior body 6 are in contact with or close to each other in the non-bonded state is adjacent to the short side where the two terminals 7 are provided in the exterior body 6. However, it may be provided along a side other than the long side 691 (that is, another short side parallel to the short side where the two terminals 7 are provided).
　２つの端子７は、必ずしも外装体６の１つの辺から外装体６の外部へと延びる必要はなく、互いに平行な一対の辺から外装体６の外部へとそれぞれ延びていてもよい。 The two terminals 7 do not necessarily have to extend from one side of the exterior body 6 to the outside of the exterior body 6, and may extend from the pair of parallel sides to the exterior of the exterior body 6, respectively.
　正極２の正極活物質板２２の構造は、様々に変更されてよい。例えば、正極活物質板２２において、層状岩塩構造を有する複数の一次粒子の平均傾斜角は、３０°よりも大きくてもよく、０°であってもよい。あるいは、当該複数の一次粒子の構造は、層状岩塩構造以外の構造であってもよい。 The structure of the positive electrode active material plate 22 of the positive electrode 2 may be variously modified. For example, in the positive electrode active material plate 22, the average tilt angle of the plurality of primary particles having a layered rock salt structure may be larger than 30° or may be 0°. Alternatively, the structure of the plurality of primary particles may be a structure other than the layered rock salt structure.
　正極２は、樹脂を主成分とするバインダおよび正極活物質を含む正極活物質層が正極集電体２１上に塗工された塗工電極であってもよい。 The positive electrode 2 may be a coated electrode in which a positive electrode active material layer containing a binder containing a resin as a main component and a positive electrode active material is coated on the positive electrode current collector 21.
　リチウム二次電池１は、スマートカード以外の可撓性を有するデバイス（例えば、カード型デバイス）、または、シート状デバイス（例えば、衣服等に設けられたウェアラブルデバイス、もしくは、身体貼付型デバイス）における電力供給源として利用されてもよい。また、リチウム二次電池１は、上述のデバイス以外の様々な対象物（例えば、ＩｏＴモジュール）の電力供給源として利用されてもよい。 The lithium secondary battery 1 is a flexible device other than a smart card (for example, a card type device) or a sheet-like device (for example, a wearable device provided on clothes or the like, or a body sticking type device). It may be used as a power supply source. Further, the lithium secondary battery 1 may be used as a power supply source for various objects (for example, IoT module) other than the above-mentioned devices.
　上記実施の形態および各変形例における構成は、相互に矛盾しない限り適宜組み合わされてよい。 The configurations of the above-described embodiment and each modification may be appropriately combined unless they contradict each other.
　発明を詳細に描写して説明したが、既述の説明は例示的であって限定的なものではない。したがって、本発明の範囲を逸脱しない限り、多数の変形や態様が可能であるといえる。 Although the invention has been described in detail, the above description is illustrative and not restrictive. Therefore, it can be said that many modifications and modes are possible without departing from the scope of the present invention.
　本発明のリチウム二次電池は、例えば、演算処理機能を有するスマートカードにおける電力供給源等として、リチウム二次電池が利用される様々な分野で利用可能である。 The lithium secondary battery of the present invention can be used in various fields where the lithium secondary battery is used, for example, as a power supply source in a smart card having an arithmetic processing function.
　１　　リチウム二次電池
　２　　正極
　３，３ａ　　負極
　４　　セパレータ
　５　　電解液
　６　　外装体
　７　　端子
　２１　　正極集電体
　２２　　正極活物質板
　３２　　負極活物質層
　３２ａ　　負極活物質板
　６５　　第１シート部
　６６　　第２シート部
　６７　　被覆領域
　６８　　外周領域
　６８１　　第１領域
　６８２　　第２領域
　６９１　　長辺
　６９３　　折り返し線 DESCRIPTION OF SYMBOLS 1 Lithium secondary battery 2 Positive electrode 3,3a Negative electrode 4 Separator 5 Electrolyte 6 Outer package 7 Terminal 21 Positive electrode current collector 22 Positive electrode active material plate 32 Negative electrode active material layer 32a Negative electrode active material plate 65 1st sheet part 66 2nd sheet Part 67 Covering area 68 Peripheral area 681 First area 682 Second area 691 Long side 693 Folding line

Claims (10)

  1. 　薄型のリチウム二次電池であって、
    　正極と、
    　所定の重ね合わせ方向において前記正極上に配置されるセパレータと、
    　前記重ね合わせ方向において前記セパレータの前記正極とは反対側に配置される負極と、
    　前記正極、前記負極および前記セパレータに含浸する電解液と、
    　前記重ね合わせ方向の両側から前記正極および前記負極を被覆する２層のシート部を有するとともに、前記正極、前記セパレータ、前記負極および前記電解液を内部に収容する矩形シート状の外装体と、
    　前記外装体の内部にて前記正極および前記負極にそれぞれ接続されるとともに前記外装体の外部へと延びる２つの端子と、
    を備え、
    　前記外装体は、
    　前記正極、前記セパレータおよび前記負極と前記重ね合わせ方向に重なる矩形状の被覆領域と、
    　前記被覆領域の周囲を囲む矩形枠状の外周領域と、
    を備え、
    　前記外周領域は、
    　前記２つの端子が配置される辺以外の一対の辺に沿ってそれぞれ延びる帯状領域であって前記２層のシート部が接合される一対の第１領域と、
    　前記一対の第１領域のうち少なくとも一方の第１領域と前記被覆領域との間にて前記被覆領域に沿って延びる帯状領域であって前記２層のシート部が非接合状態にて接触または近接する第２領域と、
    を備える。     A thin lithium secondary battery,
    The positive electrode,
    A separator disposed on the positive electrode in a predetermined stacking direction,
    A negative electrode arranged on the side opposite to the positive electrode of the separator in the stacking direction,
    An electrolyte solution impregnating the positive electrode, the negative electrode and the separator,
    A rectangular sheet-shaped exterior body that has a two-layer sheet portion that covers the positive electrode and the negative electrode from both sides in the stacking direction, and that accommodates the positive electrode, the separator, the negative electrode, and the electrolytic solution inside,
    Two terminals connected to the positive electrode and the negative electrode inside the exterior body and extending to the outside of the exterior body;
    Equipped with
    The exterior body is
    A rectangular coating region that overlaps the positive electrode, the separator, and the negative electrode in the stacking direction,
    A rectangular frame-shaped outer peripheral region surrounding the periphery of the covered region,
    Equipped with
    The outer peripheral area is
    A pair of first regions, each of which is a strip-shaped region extending along a pair of sides other than the side on which the two terminals are arranged, and to which the two-layer sheet portions are joined;
    A strip-shaped region extending along the covering region between at least one of the pair of first regions and the covering region, and the two-layer sheet portions are in contact with or close to each other in a non-bonded state. A second area to
    Equipped with.
  2. 　請求項１に記載のリチウム二次電池であって、
    　前記一対の辺に垂直な幅方向における前記正極の活物質領域の幅である正極活物質幅と前記負極の活物質領域の幅である負極活物質幅とが異なる場合は、前記正極活物質幅および前記負極活物質幅のうち小さい方を除数とし、前記正極活物質幅と前記負極活物質幅とが同じである場合は前記正極活物質幅および前記負極活物質幅のうちいずれか一方を除数として、
    　前記一対の第１領域のうち一方の第１領域と前記被覆領域との間にのみ前記第２領域が存在する場合は前記第２領域の幅を被除数とし、前記一対の第１領域の双方と前記被覆領域との間に一対の前記第２領域が存在する場合は前記一対の第２領域の合計幅を被除数として、
    　前記被除数を前記除数により除算した値は、０．０２以上かつ１以下である。     The lithium secondary battery according to claim 1, wherein
    When the positive electrode active material width, which is the width of the positive electrode active material area in the width direction perpendicular to the pair of sides, and the negative electrode active material width, which is the width of the negative electrode active material area, are different, the positive electrode active material width And the smaller one of the negative electrode active material widths is a divisor, and when the positive electrode active material width and the negative electrode active material width are the same, one of the positive electrode active material width and the negative electrode active material width is a divisor. As
    When the second region exists only between the one first region and the covering region of the pair of first regions, the width of the second region is taken as the dividend, and both of the pair of first regions are included. When there is a pair of the second regions between the covering region and the total width of the pair of second regions as a dividend,
    A value obtained by dividing the dividend by the divisor is 0.02 or more and 1 or less.
  3. 　請求項１または２に記載のリチウム二次電池であって、
    　前記少なくとも一方の第１領域は、前記一対の辺に平行に延びる折り返し線にて幅方向に折り返されている。     The lithium secondary battery according to claim 1 or 2, wherein
    The at least one first region is folded back in the width direction by a folding line extending parallel to the pair of sides.
  4. 　請求項３に記載のリチウム二次電池であって、
    　前記折り返し線は、前記少なくとも一方の第１領域の幅方向の中央、または、前記少なくとも一方の第１領域の幅方向の中央に対して前記第２領域の反対側に位置する。     The lithium secondary battery according to claim 3, wherein
    The folding line is located on the opposite side of the second region with respect to the center of the at least one first region in the width direction or the center of the at least one first region in the width direction.
  5. 　請求項３に記載のリチウム二次電池であって、
    　前記折り返し線は、前記少なくとも一方の第１領域の幅方向の中央と前記第２領域との間に位置する。     The lithium secondary battery according to claim 3, wherein
    The folding line is located between the center of the at least one first region in the width direction and the second region.
  6. 　請求項１ないし５のいずれか１つに記載のリチウム二次電池であって、
    　前記正極は、
    　導電性を有するシート状の集電体と、
    　リチウム複合酸化物を含む板状セラミック焼結体である活物質板と、
    を備える。     The lithium secondary battery according to any one of claims 1 to 5,
    The positive electrode is
    A sheet-shaped current collector having conductivity,
    An active material plate which is a plate-shaped ceramic sintered body containing a lithium composite oxide,
    Equipped with.
  7. 　請求項６に記載のリチウム二次電池であって、
    　前記活物質板は、層状岩塩構造を有する複数の一次粒子が結合した構造を有しており、
    　前記複数の一次粒子の平均傾斜角は、０°よりも大きく、かつ、３０°以下であり、
    　前記平均傾斜角は、前記複数の一次粒子の（００３）面と前記活物質板の主面とが成す角度の平均値である。     The lithium secondary battery according to claim 6, wherein
    The active material plate has a structure in which a plurality of primary particles having a layered rock salt structure are bonded,
    The average tilt angle of the plurality of primary particles is greater than 0° and 30° or less,
    The average tilt angle is an average value of angles formed by the (003) planes of the plurality of primary particles and the main surface of the active material plate.
  8. 　請求項１ないし７のいずれか１つに記載のリチウム二次電池であって、
    　シート状デバイス、または、可撓性を有するデバイスにおける電力供給源として利用される。     The lithium secondary battery according to any one of claims 1 to 7,
    It is used as a power supply source in a sheet-shaped device or a flexible device.
  9. 　請求項８に記載のリチウム二次電池であって、
    　前記可撓性を有するデバイスであるスマートカードにおける電力供給源として利用される。     The lithium secondary battery according to claim 8, wherein
    It is used as a power supply source in a smart card which is the flexible device.
  10. 　請求項１ないし９のいずれか１つに記載のリチウム二次電池であって、
    　製造の際に加熱しつつ加圧する工程が施される対象デバイスにおける電力供給源として利用される。     The lithium secondary battery according to any one of claims 1 to 9,
    It is used as a power supply source in a target device to which a step of heating and pressurizing is performed during manufacturing.
PCT/JP2019/044550 2018-12-18 2019-11-13 Lithium secondary battery WO2020129481A1 (en)

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